1. Infrastructure
This specification depends on the Infra Standard. [INFRA]
Some of the terms used in this specification are defined in Encoding, Selectors, Web IDL, XML, and Namespaces in XML. [ENCODING] [SELECTORS4] [WEBIDL] [XML] [XML-NAMES]
When extensions are needed, the DOM Standard can be updated accordingly, or a new standard can be written that hooks into the provided extensibility hooks for applicable specifications.
1.1. Trees
A tree is a finite hierarchical tree structure. In tree order is preorder, depth-first traversal of a tree.
An object that participates in a tree has a parent, which is either null or an object, and has children, which is an ordered set of objects. An object A whose parent is object B is a child of B.
The root of an object is itself, if its parent is null, or else it is the root of its parent. The root of a tree is any object participating in that tree whose parent is null.
An object A is called a descendant of an object B, if either A is a child of B or A is a child of an object C that is a descendant of B.
An inclusive descendant is an object or one of its descendants.
An object A is called an ancestor of an object B if and only if B is a descendant of A.
An inclusive ancestor is an object or one of its ancestors.
An object A is called a sibling of an object B, if and only if B and A share the same non-null parent.
An inclusive sibling is an object or one of its siblings.
An object A is preceding an object B if A and B are in the same tree and A comes before B in tree order.
An object A is following an object B if A and B are in the same tree and A comes after B in tree order.
The first child of an object is its first child or null if it has no children.
The last child of an object is its last child or null if it has no children.
The previous sibling of an object is its first preceding sibling or null if it has no preceding sibling.
The next sibling of an object is its first following sibling or null if it has no following sibling.
The index of an object is its number of preceding siblings, or 0 if it has none.
1.2. Ordered sets
The ordered set parser takes a string input and then runs these steps:
-
Let inputTokens be the result of splitting input on ASCII whitespace.
-
Let tokens be a new ordered set.
- Return tokens.
The ordered set serializer takes a set and returns the concatenation of set using U+0020 SPACE.
1.3. Selectors
To scope-match a selectors string selectors against a node, run these steps:
-
Let s be the result of parse a selector selectors. [SELECTORS4]
-
If s is failure, then throw a "
SyntaxError
"DOMException
. -
Return the result of match a selector against a tree with s and node’s root using scoping root node. [SELECTORS4].
Support for namespaces within selectors is not planned and will not be added.
1.4. Namespaces
To validate a qualifiedName, throw an
"InvalidCharacterError
" DOMException
if qualifiedName does not match
the QName
production.
To validate and extract a namespace and qualifiedName, run these steps:
-
If namespace is the empty string, then set it to null.
-
Validate qualifiedName.
-
Let prefix be null.
-
Let localName be qualifiedName.
-
If qualifiedName contains a U+003A (:), then:
-
Let splitResult be the result of running strictly split given qualifiedName and U+003A (:).
-
Set prefix to splitResult[0].
-
Set localName to splitResult[1].
-
-
If prefix is non-null and namespace is null, then throw a "
NamespaceError
"DOMException
. -
If prefix is "
xml
" and namespace is not the XML namespace, then throw a "NamespaceError
"DOMException
. -
If either qualifiedName or prefix is "
xmlns
" and namespace is not the XMLNS namespace, then throw a "NamespaceError
"DOMException
. -
If namespace is the XMLNS namespace and neither qualifiedName nor prefix is "
xmlns
", then throw a "NamespaceError
"DOMException
. -
Return namespace, prefix, and localName.
2. Events
2.1. Introduction to "DOM Events"
Throughout the web platform events are dispatched to objects to signal an
occurrence, such as network activity or user interaction. These objects implement the EventTarget
interface and can therefore add event listeners to observe events by calling addEventListener()
:
obj. addEventListener( "load" , imgFetched) function imgFetched( ev) { // great success …}
Event listeners can be removed
by utilizing the removeEventListener()
method, passing the same arguments.
Alternatively, event listeners can be removed by passing an AbortSignal
to addEventListener()
and calling abort()
on the controller
owning the signal.
Events are objects too and implement the Event
interface (or a derived interface). In the example above ev is the event. ev is
passed as an argument to the event listener’s callback (typically a JavaScript Function as shown above). Event listeners key off the event’s type
attribute value
("load
" in the above example). The event’s target
attribute value returns the
object to which the event was dispatched (obj above).
Although events are typically dispatched by the user agent as the result of user interaction or the completion of some task, applications can dispatch events themselves by using what are commonly known as synthetic events:
// add an appropriate event listener obj. addEventListener( "cat" , function ( e) { process( e. detail) }) // create and dispatch the event var event= new CustomEvent( "cat" , { "detail" : { "hazcheeseburger" : true }}) obj. dispatchEvent( event)
Apart from signaling, events are
sometimes also used to let an application control what happens next in an
operation. For instance as part of form submission an event whose type
attribute value is
"submit
" is dispatched. If this event’s preventDefault()
method is
invoked, form submission will be terminated. Applications who wish to make
use of this functionality through events dispatched by the application
(synthetic events) can make use of the return value of the dispatchEvent()
method:
if ( obj. dispatchEvent( event)) { // event was not canceled, time for some magic …}
When an event is dispatched to an object that participates in a tree (e.g., an element), it can reach event listeners on that object’s ancestors too. Effectively, all the object’s inclusive ancestor event listeners whose capture is true are invoked, in tree order. And then, if event’s bubbles
is true, all the object’s inclusive ancestor event listeners whose capture is false
are invoked, now in reverse tree order.
Let’s look at an example of how events work in a tree:
<!doctype html> < html > < head > < title > Boring example</ title > </ head > < body > < p > Hello< span id = x > world</ span > !</ p > < script > function test( e) { debug( e. target, e. currentTarget, e. eventPhase) } document. addEventListener( "hey" , test, { capture: true }) document. body. addEventListener( "hey" , test) var ev= new Event( "hey" , { bubbles: true }) document. getElementById( "x" ). dispatchEvent( ev) </ script > </ body > </ html >
The debug
function will be invoked twice. Each time the event’s target
attribute value will be the span
element. The first time currentTarget
attribute’s value will be the document, the second time the body
element. eventPhase
attribute’s value switches from CAPTURING_PHASE
to BUBBLING_PHASE
. If an event listener was registered
for the span
element, eventPhase
attribute’s value would have
been AT_TARGET
.
2.2. Interface Event
[Exposed=*]interface {
Event (
constructor DOMString ,
type optional EventInit = {});
eventInitDict readonly attribute DOMString type ;readonly attribute EventTarget ?target ;readonly attribute EventTarget ?srcElement ; // legacyreadonly attribute EventTarget ?currentTarget ;sequence <EventTarget >composedPath ();const unsigned short NONE = 0;const unsigned short CAPTURING_PHASE = 1;const unsigned short AT_TARGET = 2;const unsigned short BUBBLING_PHASE = 3;readonly attribute unsigned short eventPhase ;undefined stopPropagation ();attribute boolean cancelBubble ; // legacy alias of .stopPropagation()undefined stopImmediatePropagation ();readonly attribute boolean bubbles ;readonly attribute boolean cancelable ;attribute boolean returnValue ; // legacyundefined preventDefault ();readonly attribute boolean defaultPrevented ;readonly attribute boolean composed ; [LegacyUnforgeable ]readonly attribute boolean isTrusted ;readonly attribute DOMHighResTimeStamp timeStamp ;undefined initEvent (DOMString ,
type optional boolean =
bubbles false ,optional boolean =
cancelable false ); // legacy };dictionary {
EventInit boolean =
bubbles false ;boolean =
cancelable false ;boolean =
composed false ; };
An Event
object is simply named an event. It allows for
signaling that something has occurred, e.g., that an image has completed downloading.
A potential event target is null or an EventTarget
object.
An event has an associated target (a potential event target). Unless stated otherwise it is null.
An event has an associated relatedTarget (a potential event target). Unless stated otherwise it is null.
Other specifications use relatedTarget to define a relatedTarget
attribute. [UIEVENTS]
An event has an associated touch target list (a list of zero or more potential event targets). Unless stated otherwise it is the empty list.
The touch target list is for the exclusive use of defining the TouchEvent
interface and related interfaces. [TOUCH-EVENTS]
An event has an associated path. A path is a list of structs. Each struct consists of an invocation target (an EventTarget
object), an invocation-target-in-shadow-tree (a boolean), a shadow-adjusted target (a potential event target), a relatedTarget (a potential event target), a touch target list (a list of potential event targets), a root-of-closed-tree (a boolean), and
a slot-in-closed-tree (a boolean). A path is initially
the empty list.
event = new Event(type [, eventInitDict])
- Returns a new event whose
type
attribute value is set to type. The eventInitDict argument allows for setting thebubbles
andcancelable
attributes via object members of the same name. event .
type
- Returns the type of event, e.g.
"
click
", "hashchange
", or "submit
". event .
target
- Returns the object to which event is dispatched (its target).
event .
currentTarget
- Returns the object whose event listener’s callback is currently being invoked.
event .
composedPath()
- Returns the invocation target objects of event’s path (objects on which listeners will be invoked), except for any nodes in shadow trees of which the shadow root’s mode is "
closed
" that are not reachable from event’scurrentTarget
. event .
eventPhase
- Returns the event’s phase, which is one of
NONE
,CAPTURING_PHASE
,AT_TARGET
, andBUBBLING_PHASE
. event . stopPropagation()
- When dispatched in a tree, invoking this method prevents event from reaching any objects other than the current object.
event . stopImmediatePropagation()
- Invoking this method prevents event from reaching any registered event listeners after the current one finishes running and, when dispatched in a tree, also prevents event from reaching any other objects.
event .
bubbles
- Returns true or false depending on how event was initialized. True if event goes through its target’s ancestors in reverse tree order; otherwise false.
event .
cancelable
- Returns true or false depending on how event was initialized. Its return
value does not always carry meaning, but true can indicate that part of the operation
during which event was dispatched, can be canceled by invoking the
preventDefault()
method. event . preventDefault()
- If invoked when the
cancelable
attribute value is true, and while executing a listener for the event withpassive
set to false, signals to the operation that caused event to be dispatched that it needs to be canceled. event .
defaultPrevented
- Returns true if
preventDefault()
was invoked successfully to indicate cancelation; otherwise false. event .
composed
- Returns true or false depending on how event was initialized. True if event invokes listeners past a
ShadowRoot
node that is the root of its target; otherwise false. event .
isTrusted
- Returns true if event was dispatched by the user agent, and false otherwise.
event .
timeStamp
- Returns the event’s timestamp as the number of milliseconds measured relative to the occurrence.
The type
attribute must return the value it was
initialized to. When an event is created the attribute must be initialized to the empty
string.
The target
getter steps are to return this’s target.
The srcElement
getter steps are to return this’s target.
The currentTarget
attribute must return the value it
was initialized to. When an event is created the attribute must be initialized to null.
The composedPath()
method steps are:
-
Let composedPath be an empty list.
-
If path is empty, then return composedPath.
-
Let currentTarget be this’s
currentTarget
attribute value. -
Append currentTarget to composedPath.
-
Let currentTargetIndex be 0.
-
Let currentTargetHiddenSubtreeLevel be 0.
-
Let index be path’s size − 1.
-
While index is greater than or equal to 0:
-
If path[index]'s root-of-closed-tree is true, then increase currentTargetHiddenSubtreeLevel by 1.
-
If path[index]'s invocation target is currentTarget, then set currentTargetIndex to index and break.
-
If path[index]'s slot-in-closed-tree is true, then decrease currentTargetHiddenSubtreeLevel by 1.
-
Decrease index by 1.
-
-
Let currentHiddenLevel and maxHiddenLevel be currentTargetHiddenSubtreeLevel.
-
Set index to currentTargetIndex − 1.
-
While index is greater than or equal to 0:
-
If path[index]'s root-of-closed-tree is true, then increase currentHiddenLevel by 1.
-
If currentHiddenLevel is less than or equal to maxHiddenLevel, then prepend path[index]'s invocation target to composedPath.
-
If path[index]'s slot-in-closed-tree is true, then:
-
Decrease currentHiddenLevel by 1.
-
If currentHiddenLevel is less than maxHiddenLevel, then set maxHiddenLevel to currentHiddenLevel.
-
-
Decrease index by 1.
-
-
Set currentHiddenLevel and maxHiddenLevel to currentTargetHiddenSubtreeLevel.
-
Set index to currentTargetIndex + 1.
-
While index is less than path’s size:
-
If path[index]'s slot-in-closed-tree is true, then increase currentHiddenLevel by 1.
-
If currentHiddenLevel is less than or equal to maxHiddenLevel, then append path[index]'s invocation target to composedPath.
-
If path[index]'s root-of-closed-tree is true, then:
-
Decrease currentHiddenLevel by 1.
-
If currentHiddenLevel is less than maxHiddenLevel, then set maxHiddenLevel to currentHiddenLevel.
-
-
Increase index by 1.
-
-
Return composedPath.
The eventPhase
attribute must return the value it was
initialized to, which must be one of the following:
NONE
(numeric value 0)- Events not currently dispatched are in this phase.
CAPTURING_PHASE
(numeric value 1)- When an event is dispatched to an object that participates in a tree it will be in this phase before it reaches its target.
AT_TARGET
(numeric value 2)- When an event is dispatched it will be in this phase on its target.
BUBBLING_PHASE
(numeric value 3)- When an event is dispatched to an object that participates in a tree it will be in this phase after it reaches its target.
Initially the attribute must be initialized to NONE
.
Each event has the following associated flags that are all initially unset:
- stop propagation flag
- stop immediate propagation flag
- canceled flag
- in passive listener flag
- composed flag
- initialized flag
- dispatch flag
The stopPropagation()
method steps are to set this’s stop propagation flag.
The cancelBubble
getter steps are to return true if this’s stop propagation flag is set; otherwise false.
The cancelBubble
setter steps are to set this’s stop propagation flag if
the given value is true; otherwise do nothing.
The stopImmediatePropagation()
method steps are to set this’s stop propagation flag and this’s stop immediate propagation flag.
The bubbles
and cancelable
attributes must return the values they were
initialized to.
To set the canceled flag, given an event event, if event’s cancelable
attribute value is true and event’s in passive listener flag is unset, then set event’s canceled flag, and do
nothing otherwise.
The returnValue
getter steps are to return false if this’s canceled flag is set; otherwise true.
The returnValue
setter steps are to set the canceled flag with this if
the given value is false; otherwise do nothing.
The preventDefault()
method steps are to set the canceled flag with this.
There are scenarios where invoking preventDefault()
has no
effect. User agents are encouraged to log the precise cause in a developer console, to aid
debugging.
The defaultPrevented
getter steps are to return true
if this’s canceled flag is set; otherwise false.
The composed
getter steps are to return true if this’s composed flag is set; otherwise false.
The isTrusted
attribute must return the value it was
initialized to. When an event is created the attribute must be initialized to false.
isTrusted
is a convenience that indicates whether an event is dispatched by the user agent (as opposed to using dispatchEvent()
). The sole legacy exception is click()
, which causes
the user agent to dispatch an event whose isTrusted
attribute is initialized to
false.
The timeStamp
attribute must return the value it was
initialized to.
To initialize an event, with type, bubbles, and cancelable, run these steps:
-
Set event’s initialized flag.
-
Unset event’s stop propagation flag, stop immediate propagation flag, and canceled flag.
-
Set event’s
isTrusted
attribute to false. -
Set event’s target to null.
-
Set event’s
type
attribute to type. -
Set event’s
bubbles
attribute to bubbles. -
Set event’s
cancelable
attribute to cancelable.
The initEvent(type, bubbles, cancelable)
method steps are:
-
If this’s dispatch flag is set, then return.
-
Initialize this with type, bubbles, and cancelable.
initEvent()
is redundant with event constructors and
incapable of setting composed
. It has to be supported for legacy content.
2.3. Legacy extensions to the Window
interface
partial interface Window { [Replaceable ]readonly attribute (Event or undefined )event ; // legacy };
Each Window
object has an associated current event (undefined or an Event
object). Unless stated otherwise it is undefined.
The event
getter steps are to return this’s current event.
Web developers are strongly encouraged to instead rely on the Event
object passed
to event listeners, as that will result in more portable code. This attribute is not available in
workers or worklets, and is inaccurate for events dispatched in shadow trees.
2.4. Interface CustomEvent
[Exposed=*]interface :
CustomEvent Event {(
constructor DOMString ,
type optional CustomEventInit = {});
eventInitDict readonly attribute any detail ;undefined initCustomEvent (DOMString ,
type optional boolean =
bubbles false ,optional boolean =
cancelable false ,optional any =
detail null ); // legacy };dictionary :
CustomEventInit EventInit {any =
detail null ; };
Events using the CustomEvent
interface can be used to carry custom data.
event = new CustomEvent(type [, eventInitDict])
- Works analogously to the constructor for
Event
except that the eventInitDict argument now allows for setting thedetail
attribute too. event .
detail
- Returns any custom data event was created with. Typically used for synthetic events.
The detail
attribute must return the value it
was initialized to.
The initCustomEvent(type, bubbles, cancelable, detail)
method steps are:
-
If this’s dispatch flag is set, then return.
-
Initialize this with type, bubbles, and cancelable.
2.5. Constructing events
Specifications may define event constructing steps for all or some events. The algorithm is passed an event event and an EventInit
eventInitDict as indicated in the inner event creation steps.
This construct can be used by Event
subclasses that have a more complex structure
than a simple 1:1 mapping between their initializing dictionary members and IDL attributes.
When a constructor of the Event
interface, or of an interface that inherits from the Event
interface, is invoked, these steps
must be run, given the arguments type and eventInitDict:
-
Let event be the result of running the inner event creation steps with this interface, null, now, and eventInitDict.
-
Initialize event’s
type
attribute to type. -
Return event.
To create an event using eventInterface, which must be either Event
or an interface that inherits from
it, and optionally given a realm realm, run these steps:
-
If realm is not given, then set it to null.
-
Let dictionary be the result of converting the JavaScript value undefined to the dictionary type accepted by eventInterface’s constructor. (This dictionary type will either be
EventInit
or a dictionary that inherits from it.)This does not work if members are required; see whatwg/dom#600.
-
Let event be the result of running the inner event creation steps with eventInterface, realm, the time of the occurrence that the event is signaling, and dictionary.
In macOS the time of the occurrence for input actions is available via the
timestamp
property ofNSEvent
objects. -
Initialize event’s
isTrusted
attribute to true. -
Return event.
Create an event is meant to be used by other specifications which need to separately create and dispatch events, instead of simply firing them. It ensures the event’s attributes are initialized to the correct defaults.
The inner event creation steps, given an eventInterface, realm, time, and dictionary, are as follows:
-
Let event be the result of creating a new object using eventInterface. If realm is non-null, then use that realm; otherwise, use the default behavior defined in Web IDL.
As of the time of this writing Web IDL does not yet define any default behavior; see whatwg/webidl#135.
-
Set event’s initialized flag.
-
Initialize event’s
timeStamp
attribute to the relative high resolution coarse time given time and event’s relevant global object. -
For each member → value in dictionary, if event has an attribute whose identifier is member, then initialize that attribute to value.
-
Run the event constructing steps with event and dictionary.
-
Return event.
2.6. Defining event interfaces
In general, when defining a new interface that inherits from Event
please always ask
feedback from the WHATWG or the W3C WebApps WG community.
The CustomEvent
interface can be used as starting point.
However, do not introduce any init*Event()
methods as they are redundant with constructors. Interfaces that inherit
from the Event
interface that have such a method only have it
for historical reasons.
2.7. Interface EventTarget
[Exposed=*]interface {
EventTarget constructor ();undefined addEventListener (DOMString ,
type EventListener ?,
callback optional (AddEventListenerOptions or boolean )= {});
options undefined removeEventListener (DOMString ,
type EventListener ?,
callback optional (EventListenerOptions or boolean )= {});
options boolean dispatchEvent (Event ); };
event callback interface {
EventListener undefined (
handleEvent Event ); };
event dictionary {
EventListenerOptions boolean =
capture false ; };dictionary :
AddEventListenerOptions EventListenerOptions {boolean ;
passive boolean =
once false ;AbortSignal ; };
signal
An EventTarget
object represents a target to which an event can be dispatched when something has occurred.
Each EventTarget
object has an associated event listener list (a list of zero or more event listeners). It is initially the empty list.
An event listener can be used to observe a specific event and consists of:
- type (a string)
- callback (null or an
EventListener
object) - capture (a boolean, initially false)
- passive (null or a boolean, initially null)
- once (a boolean, initially false)
- signal (null or an
AbortSignal
object) - removed (a boolean for bookkeeping purposes, initially false)
Although callback is an EventListener
object, an event listener is a broader concept as can be seen above.
Each EventTarget
object also has an associated get the parent algorithm,
which takes an event event, and returns an EventTarget
object. Unless
specified otherwise it returns null.
Nodes, shadow roots, and documents override the get the parent algorithm.
Each EventTarget
object can have an associated activation behavior algorithm. The activation behavior algorithm is passed an event, as indicated in the dispatch algorithm.
This exists because user agents perform certain actions for certain EventTarget
objects, e.g., the area
element, in response to synthetic MouseEvent
events whose type
attribute is click
. Web compatibility prevented it
from being removed and it is now the enshrined way of defining an activation of something. [HTML]
Each EventTarget
object that has activation behavior, can additionally
have both (not either) a legacy-pre-activation behavior algorithm
and a legacy-canceled-activation behavior algorithm.
These algorithms only exist for checkbox and radio input
elements and
are not to be used for anything else. [HTML]
target = new EventTarget();
-
Creates a new
EventTarget
object, which can be used by developers to dispatch and listen for events. target . addEventListener(type, callback [, options])
-
Appends an event listener for events whose
type
attribute value is type. The callback argument sets the callback that will be invoked when the event is dispatched.The options argument sets listener-specific options. For compatibility this can be a boolean, in which case the method behaves exactly as if the value was specified as options’s
capture
.When set to true, options’s
capture
prevents callback from being invoked when the event’seventPhase
attribute value isBUBBLING_PHASE
. When false (or not present), callback will not be invoked when event’seventPhase
attribute value isCAPTURING_PHASE
. Either way, callback will be invoked if event’seventPhase
attribute value isAT_TARGET
.When set to true, options’s
passive
indicates that the callback will not cancel the event by invokingpreventDefault()
. This is used to enable performance optimizations described in § 2.8 Observing event listeners.When set to true, options’s
once
indicates that the callback will only be invoked once after which the event listener will be removed.If an
AbortSignal
is passed for options’ssignal
, then the event listener will be removed when signal is aborted.The event listener is appended to target’s event listener list and is not appended if it has the same type, callback, and capture.
target . removeEventListener(type, callback [, options])
-
Removes the event listener in target’s event listener list with the same type, callback, and options.
target . dispatchEvent(event)
-
Dispatches a synthetic event event to target and returns true if either event’s
cancelable
attribute value is false or itspreventDefault()
method was not invoked; otherwise false.
To flatten options, run these steps:
-
If options is a boolean, then return options.
-
Return options["
capture
"].
To flatten more options, run these steps:
-
Let capture be the result of flattening options.
-
Let once be false.
-
Let passive and signal be null.
-
If options is a dictionary, then:
-
Return capture, passive, once, and signal.
The new EventTarget()
constructor steps are to do nothing.
Because of the defaults stated elsewhere, the returned EventTarget
's get the parent algorithm will return null, and it will have no activation behavior, legacy-pre-activation behavior,
or legacy-canceled-activation behavior.
In the future we could allow custom get the parent algorithms. Let us know
if this would be useful for your programs. For now, all author-created EventTarget
s do not
participate in a tree structure.
The default passive value, given an event type type and an EventTarget
eventTarget, is determined as follows:
-
Return true if all of the following are true:
-
type is one of "
touchstart
", "touchmove
", "wheel
", or "mousewheel
". [TOUCH-EVENTS] [UIEVENTS] -
eventTarget is a
Window
object, or is a node whose node document is eventTarget, or is a node whose node document’s document element is eventTarget, or is a node whose node document’s body element is eventTarget. [HTML]
-
-
Return false.
To add an event listener, given an EventTarget
object eventTarget and an event listener listener, run these steps:
-
If eventTarget is a
ServiceWorkerGlobalScope
object, its service worker’s script resource’s has ever been evaluated flag is set, and listener’s type matches thetype
attribute value of any of the service worker events, then report a warning to the console that this might not give the expected results. [SERVICE-WORKERS] -
If listener’s signal is not null and is aborted, then return.
-
If listener’s callback is null, then return.
-
If listener’s passive is null, then set it to the default passive value given listener’s type and eventTarget.
-
If eventTarget’s event listener list does not contain an event listener whose type is listener’s type, callback is listener’s callback, and capture is listener’s capture, then append listener to eventTarget’s event listener list.
-
If listener’s signal is not null, then add the following abort steps to it:
- Remove an event listener with eventTarget and listener.
The add an event listener concept exists to ensure event handlers use the same code path. [HTML]
The addEventListener(type, callback, options)
method steps are:
-
Let capture, passive, once, and signal be the result of flattening more options.
-
Add an event listener with this and an event listener whose type is type, callback is callback, capture is capture, passive is passive, once is once, and signal is signal.
To remove an event listener, given an EventTarget
object eventTarget and an event listener listener, run these steps:
-
If eventTarget is a
ServiceWorkerGlobalScope
object and its service worker’s set of event types to handle contains listener’s type, then report a warning to the console that this might not give the expected results. [SERVICE-WORKERS] -
Set listener’s removed to true and remove listener from eventTarget’s event listener list.
HTML needs this to define event handlers. [HTML]
To remove all event listeners, given an EventTarget
object eventTarget, for each listener of eventTarget’s event listener list, remove an event listener with eventTarget and listener.
HTML needs this to define document.open()
. [HTML]
The removeEventListener(type, callback, options)
method steps are:
-
Let capture be the result of flattening options.
-
If this’s event listener list contains an event listener whose type is type, callback is callback, and capture is capture, then remove an event listener with this and that event listener.
The event listener list will not contain multiple event listeners with equal type, callback, and capture, as add an event listener prevents that.
The dispatchEvent(event)
method steps
are:
-
If event’s dispatch flag is set, or if its initialized flag is not set, then throw an "
InvalidStateError
"DOMException
. -
Initialize event’s
isTrusted
attribute to false. -
Return the result of dispatching event to this.
2.8. Observing event listeners
In general, developers do not expect the presence of an event listener to be observable. The impact of an event listener is determined by its callback. That is, a developer adding a no-op event listener would not expect it to have any side effects.
Unfortunately, some event APIs have been designed such that implementing them efficiently
requires observing event listeners. This can make the presence of listeners observable in
that even empty listeners can have a dramatic performance impact on the behavior of the application.
For example, touch and wheel events which can be used to block asynchronous scrolling. In some cases
this problem can be mitigated by specifying the event to be cancelable
only when there is
at least one non-passive
listener. For example,
non-passive
TouchEvent
listeners must block scrolling, but if all
listeners are passive
then scrolling can be allowed to start in parallel by making the TouchEvent
uncancelable (so that calls to preventDefault()
are ignored). So code dispatching an event is able to observe the absence
of non-passive
listeners, and use that to clear the cancelable
property of the event being dispatched.
Ideally, any new event APIs are defined such that they do not need this property. (Use whatwg/dom for discussion.)
To legacy-obtain service worker fetch event listener callbacks given a ServiceWorkerGlobalScope
global, run these steps. They return a list of EventListener
objects.
2.9. Dispatching events
To dispatch an event to a target, with an optional legacy target override flag and an optional legacyOutputDidListenersThrowFlag, run these steps:
-
Set event’s dispatch flag.
-
Let targetOverride be target, if legacy target override flag is not given, and target’s associated
Document
otherwise. [HTML]legacy target override flag is only used by HTML and only when target is a
Window
object. -
Let activationTarget be null.
-
Let relatedTarget be the result of retargeting event’s relatedTarget against target.
-
If target is not relatedTarget or target is event’s relatedTarget, then:
-
Let touchTargets be a new list.
-
For each touchTarget of event’s touch target list, append the result of retargeting touchTarget against target to touchTargets.
-
Append to an event path with event, target, targetOverride, relatedTarget, touchTargets, and false.
-
Let isActivationEvent be true, if event is a
MouseEvent
object and event’stype
attribute is "click
"; otherwise false. -
If isActivationEvent is true and target has activation behavior, then set activationTarget to target.
-
Let slottable be target, if target is a slottable and is assigned, and null otherwise.
-
Let slot-in-closed-tree be false.
-
Let parent be the result of invoking target’s get the parent with event.
-
While parent is non-null:
-
If slottable is non-null:
-
Assert: parent is a slot.
-
Set slottable to null.
-
If parent’s root is a shadow root whose mode is "
closed
", then set slot-in-closed-tree to true.
-
-
If parent is a slottable and is assigned, then set slottable to parent.
-
Let relatedTarget be the result of retargeting event’s relatedTarget against parent.
-
Let touchTargets be a new list.
-
For each touchTarget of event’s touch target list, append the result of retargeting touchTarget against parent to touchTargets.
-
If parent is a
Window
object, or parent is a node and target’s root is a shadow-including inclusive ancestor of parent, then:-
If isActivationEvent is true, event’s
bubbles
attribute is true, activationTarget is null, and parent has activation behavior, then set activationTarget to parent. -
Append to an event path with event, parent, null, relatedTarget, touchTargets, and slot-in-closed-tree.
-
-
Otherwise, if parent is relatedTarget, then set parent to null.
-
Otherwise, set target to parent and then:
-
If isActivationEvent is true, activationTarget is null, and target has activation behavior, then set activationTarget to target.
-
Append to an event path with event, parent, target, relatedTarget, touchTargets, and slot-in-closed-tree.
-
-
If parent is non-null, then set parent to the result of invoking parent’s get the parent with event.
-
Set slot-in-closed-tree to false.
-
-
Let clearTargetsStruct be the last struct in event’s path whose shadow-adjusted target is non-null.
-
Let clearTargets be true if clearTargetsStruct’s shadow-adjusted target, clearTargetsStruct’s relatedTarget, or an
EventTarget
object in clearTargetsStruct’s touch target list is a node and its root is a shadow root; otherwise false. -
If activationTarget is non-null and activationTarget has legacy-pre-activation behavior, then run activationTarget’s legacy-pre-activation behavior.
-
For each struct in event’s path, in reverse order:
-
If struct’s shadow-adjusted target is non-null, then set event’s
eventPhase
attribute toAT_TARGET
. -
Otherwise, set event’s
eventPhase
attribute toCAPTURING_PHASE
. -
Invoke with struct, event, "
capturing
", and legacyOutputDidListenersThrowFlag if given.
-
-
For each struct in event’s path:
-
If struct’s shadow-adjusted target is non-null, then set event’s
eventPhase
attribute toAT_TARGET
. -
Otherwise:
-
Set event’s
eventPhase
attribute toBUBBLING_PHASE
.
-
Invoke with struct, event, "
bubbling
", and legacyOutputDidListenersThrowFlag if given.
-
-
-
Set event’s
eventPhase
attribute toNONE
. -
Set event’s
currentTarget
attribute to null. -
Set event’s path to the empty list.
-
Unset event’s dispatch flag, stop propagation flag, and stop immediate propagation flag.
-
If clearTargets, then:
-
Set event’s target to null.
-
Set event’s relatedTarget to null.
-
Set event’s touch target list to the empty list.
-
-
If activationTarget is non-null, then:
-
If event’s canceled flag is unset, then run activationTarget’s activation behavior with event.
-
Otherwise, if activationTarget has legacy-canceled-activation behavior, then run activationTarget’s legacy-canceled-activation behavior.
-
-
Return false if event’s canceled flag is set; otherwise true.
To append to an event path, given an event, invocationTarget, shadowAdjustedTarget, relatedTarget, touchTargets, and a slot-in-closed-tree, run these steps:
-
Let invocationTargetInShadowTree be false.
-
If invocationTarget is a node and its root is a shadow root, then set invocationTargetInShadowTree to true.
-
Let root-of-closed-tree be false.
-
If invocationTarget is a shadow root whose mode is "
closed
", then set root-of-closed-tree to true. -
Append a new struct to event’s path whose invocation target is invocationTarget, invocation-target-in-shadow-tree is invocationTargetInShadowTree, shadow-adjusted target is shadowAdjustedTarget, relatedTarget is relatedTarget, touch target list is touchTargets, root-of-closed-tree is root-of-closed-tree, and slot-in-closed-tree is slot-in-closed-tree.
To invoke, given a struct, event, phase, and an optional legacyOutputDidListenersThrowFlag, run these steps:
-
Set event’s target to the shadow-adjusted target of the last struct in event’s path, that is either struct or preceding struct, whose shadow-adjusted target is non-null.
-
Set event’s relatedTarget to struct’s relatedTarget.
-
Set event’s touch target list to struct’s touch target list.
-
If event’s stop propagation flag is set, then return.
-
Initialize event’s
currentTarget
attribute to struct’s invocation target. -
Let listeners be a clone of event’s
currentTarget
attribute value’s event listener list.This avoids event listeners added after this point from being run. Note that removal still has an effect due to the removed field.
-
Let invocationTargetInShadowTree be struct’s invocation-target-in-shadow-tree.
-
Let found be the result of running inner invoke with event, listeners, phase, invocationTargetInShadowTree, and legacyOutputDidListenersThrowFlag if given.
-
If found is false and event’s
isTrusted
attribute is true, then:-
Let originalEventType be event’s
type
attribute value. -
If event’s
type
attribute value is a match for any of the strings in the first column in the following table, set event’stype
attribute value to the string in the second column on the same row as the matching string, and return otherwise.Event type Legacy event type " animationend
"" webkitAnimationEnd
"" animationiteration
"" webkitAnimationIteration
"" animationstart
"" webkitAnimationStart
"" transitionend
"" webkitTransitionEnd
" -
Inner invoke with event, listeners, phase, invocationTargetInShadowTree, and legacyOutputDidListenersThrowFlag if given.
-
Set event’s
type
attribute value to originalEventType.
-
To inner invoke, given an event, listeners, phase, invocationTargetInShadowTree, and an optional legacyOutputDidListenersThrowFlag, run these steps:
-
Let found be false.
-
For each listener in listeners, whose removed is false:
-
If event’s
type
attribute value is not listener’s type, then continue. -
Set found to true.
-
If phase is "
capturing
" and listener’s capture is false, then continue. -
If phase is "
bubbling
" and listener’s capture is true, then continue. -
If listener’s once is true, then remove an event listener given event’s
currentTarget
attribute value and listener. -
Let global be listener callback’s associated realm’s global object.
-
Let currentEvent be undefined.
-
If global is a
Window
object, then:-
Set currentEvent to global’s current event.
-
If invocationTargetInShadowTree is false, then set global’s current event to event.
-
-
If listener’s passive is true, then set event’s in passive listener flag.
-
If global is a
Window
object, then record timing info for event listener given event and listener. -
Call a user object’s operation with listener’s callback, "
handleEvent
", « event », and event’scurrentTarget
attribute value. If this throws an exception exception, then:-
Report exception for listener’s callback’s corresponding JavaScript object’s associated realm’s global object.
-
Set legacyOutputDidListenersThrowFlag if given.
The legacyOutputDidListenersThrowFlag is only used by Indexed Database API. [INDEXEDDB]
-
-
Unset event’s in passive listener flag.
-
If global is a
Window
object, then set global’s current event to currentEvent. -
If event’s stop immediate propagation flag is set, then break.
-
-
Return found.
2.10. Firing events
To fire an event named e at target, optionally using an eventConstructor, with a description of how IDL attributes are to be initialized, and a legacy target override flag, run these steps:
-
If eventConstructor is not given, then let eventConstructor be
Event
. -
Let event be the result of creating an event given eventConstructor, in the relevant realm of target.
-
Initialize event’s
type
attribute to e. -
Initialize any other IDL attributes of event as described in the invocation of this algorithm.
This also allows for the
isTrusted
attribute to be set to false. -
Return the result of dispatching event at target, with legacy target override flag set if set.
Fire in the context of DOM is short for creating, initializing, and dispatching an event. Fire an event makes that process easier to write down.
If the event needs its bubbles
or cancelable
attribute initialized,
one could write "fire an event named submit
at target with its cancelable
attribute initialized to true".
Or, when a custom constructor is needed, "fire an event named click
at target using MouseEvent
with its detail
attribute initialized to 1".
Occasionally the return value is important:
-
Let doAction be the result of firing an event named
like
at target. -
If doAction is true, then …
2.11. Action versus occurrence
An event signifies an occurrence, not an action. Phrased differently, it
represents a notification from an algorithm and can be used to influence the future course
of that algorithm (e.g., through invoking preventDefault()
). Events must not be
used as actions or initiators that cause some algorithm to start running. That is not what
they are for.
This is called out here specifically because previous iterations of the DOM had a concept of "default actions" associated with events that gave folks all the wrong ideas. Events do not represent or cause actions, they can only be used to influence an ongoing one.
3. Aborting ongoing activities
Though promises do not have a built-in aborting mechanism, many APIs using them require abort
semantics. AbortController
is meant to support these requirements by providing an abort()
method that toggles the state of a corresponding AbortSignal
object.
The API which wishes to support aborting can accept an AbortSignal
object, and use its state to
determine how to proceed.
APIs that rely upon AbortController
are encouraged to respond to abort()
by rejecting any unsettled promise with the AbortSignal
's abort reason.
A hypothetical doAmazingness({ ... })
method could accept an AbortSignal
object
to support aborting as follows:
const controller = new AbortController();
const signal = controller. signal;
startSpinner();
doAmazingness({ ..., signal })
. then( result => ...)
. catch ( err => {
if ( err. name == 'AbortError' ) return ;
showUserErrorMessage();
})
. then(() => stopSpinner());
// …
controller. abort();
doAmazingness
could be implemented as follows:
function doAmazingness({ signal}) {
return new Promise(( resolve, reject) => {
signal. throwIfAborted();
// Begin doing amazingness, and call resolve(result) when done.
// But also, watch for signals:
signal. addEventListener( 'abort' , () => {
// Stop doing amazingness, and:
reject( signal. reason);
});
});
}
APIs that do not return promises can either react in an equivalent manner or opt to not surface
the AbortSignal
's abort reason at all. addEventListener()
is an
example of an API where the latter made sense.
APIs that require more granular control could extend both AbortController
and AbortSignal
objects according to their needs.
3.1. Interface AbortController
[Exposed=*]interface {
AbortController constructor (); [SameObject ]readonly attribute AbortSignal signal ;undefined abort (optional any ); };
reason
controller = new AbortController()
- Returns a new controller whose
signal
is set to a newly createdAbortSignal
object. controller . signal
- Returns the
AbortSignal
object associated with this object. controller . abort(reason)
- Invoking this method will store reason in this object’s
AbortSignal
's abort reason, and signal to any observers that the associated activity is to be aborted. If reason is undefined, then an "AbortError
"DOMException
will be stored.
An AbortController
object has an associated signal (an AbortSignal
object).
The new AbortController()
constructor steps are:
-
Let signal be a new
AbortSignal
object.
The signal
getter steps are to return this’s signal.
The abort(reason)
method steps are
to signal abort on this with reason if it is given.
To signal abort on an AbortController
controller with an optional reason, signal abort on controller’s signal with reason if it is given.
3.2. Interface AbortSignal
[Exposed=*]interface :
AbortSignal EventTarget { [NewObject ]static AbortSignal abort (optional any ); [
reason Exposed =(Window ,Worker ),NewObject ]static AbortSignal timeout ([EnforceRange ]unsigned long long ); [
milliseconds NewObject ]static AbortSignal _any (sequence <AbortSignal >);
signals readonly attribute boolean aborted ;readonly attribute any reason ;undefined throwIfAborted ();attribute EventHandler onabort ; };
AbortSignal . abort(reason)
- Returns an
AbortSignal
instance whose abort reason is set to reason if not undefined; otherwise to an "AbortError
"DOMException
. AbortSignal . any(signals)
- Returns an
AbortSignal
instance which will be aborted once any of signals is aborted. Its abort reason will be set to whichever one of signals caused it to be aborted. AbortSignal . timeout(milliseconds)
- Returns an
AbortSignal
instance which will be aborted in milliseconds milliseconds. Its abort reason will be set to a "TimeoutError
"DOMException
. signal . aborted
- Returns true if signal’s
AbortController
has signaled to abort; otherwise false. signal . reason
- Returns signal’s abort reason.
signal . throwIfAborted()
- Throws signal’s abort reason, if signal’s
AbortController
has signaled to abort; otherwise, does nothing.
An AbortSignal
object has an associated abort reason (a
JavaScript value), which is initially undefined.
An AbortSignal
object has associated abort algorithms, (a set of algorithms which are to be executed when it is aborted),
which is initially empty.
The abort algorithms enable APIs with complex
requirements to react in a reasonable way to abort()
. For example, a given API’s abort reason might need to be propagated to a cross-thread environment, such as a
service worker.
An AbortSignal
object has a dependent (a boolean), which is
initially false.
An AbortSignal
object has associated source signals (a weak set of AbortSignal
objects that the object is dependent on for its aborted state), which is initially empty.
An AbortSignal
object has associated dependent signals (a weak set of AbortSignal
objects that are dependent on the object for their aborted state), which is initially empty.
The static abort(reason)
method steps
are:
-
Let signal be a new
AbortSignal
object. -
Set signal’s abort reason to reason if it is given; otherwise to a new "
AbortError
"DOMException
. - Return signal.
The static timeout(milliseconds)
method
steps are:
-
Let signal be a new
AbortSignal
object. -
Let global be signal’s relevant global object.
-
Run steps after a timeout given global, "
AbortSignal-timeout
", milliseconds, and the following step:-
Queue a global task on the timer task source given global to signal abort given signal and a new "
TimeoutError
"DOMException
.
For the duration of this timeout, if signal has any event listeners registered for its
abort
event, there must be a strong reference from global to signal. -
-
Return signal.
The static any(signals)
method
steps are to return the result of creating a dependent abort signal from signals using AbortSignal
and the current realm.
The aborted
getter steps are to return true if this is aborted; otherwise false.
The reason
getter steps are to return this’s abort reason.
The throwIfAborted()
method steps are to throw this’s abort reason, if this is aborted.
This method is primarily useful for when functions accepting AbortSignal
s want to throw (or
return a rejected promise) at specific checkpoints, instead of passing along the AbortSignal
to other methods. For example, the following function allows aborting in between each attempt to
poll for a condition. This gives opportunities to abort the polling process, even though the
actual asynchronous operation (i.e.,
) does not
accept an AbortSignal
.
async function waitForCondition( func, targetValue, { signal} = {}) { while ( true ) { signal? . throwIfAborted(); const result= await func(); if ( result=== targetValue) { return ; } } }
The onabort
attribute is an event handler IDL attribute for the onabort
event handler, whose event handler event type is abort
.
Changes to an AbortSignal
object represent the wishes of the corresponding AbortController
object, but an API observing the AbortSignal
object can choose to ignore
them. For instance, if the operation has already completed.
An AbortSignal
object is aborted when its abort reason is not undefined.
To add an algorithm algorithm to an AbortSignal
object signal:
-
If signal is aborted, then return.
-
Append algorithm to signal’s abort algorithms.
To remove an algorithm algorithm from an AbortSignal
signal, remove algorithm from signal’s abort algorithms.
To signal abort, given an AbortSignal
object signal and
an optional reason:
-
If signal is aborted, then return.
-
Set signal’s abort reason to reason if it is given; otherwise to a new "
AbortError
"DOMException
. -
Let dependentSignalsToAbort be a new list.
-
For each dependentSignal of signal’s dependent signals:
-
If dependentSignal is not aborted, then:
-
Set dependentSignal’s abort reason to signal’s abort reason.
-
Append dependentSignal to dependentSignalsToAbort.
-
-
-
Run the abort steps for signal.
-
For each dependentSignal of dependentSignalsToAbort, run the abort steps for dependentSignal.
To run the abort steps for an AbortSignal
signal:
-
For each algorithm of signal’s abort algorithms: run algorithm.
-
Empty signal’s abort algorithms.
-
Fire an event named
abort
at signal.
To create a dependent abort signal from a list of AbortSignal
objects signals, using signalInterface, which must be either AbortSignal
or an
interface that inherits from it, and a realm:
-
Let resultSignal be a new object implementing signalInterface using realm.
-
For each signal of signals: if signal is aborted, then set resultSignal’s abort reason to signal’s abort reason and return resultSignal.
-
Set resultSignal’s dependent to true.
-
For each signal of signals:
-
If signal’s dependent is false, then:
-
Append signal to resultSignal’s source signals.
-
Append resultSignal to signal’s dependent signals.
-
-
Otherwise, for each sourceSignal of signal’s source signals:
-
Append sourceSignal to resultSignal’s source signals.
-
Append resultSignal to sourceSignal’s dependent signals.
-
-
Return resultSignal.
3.2.1. Garbage collection
A non-aborted dependent AbortSignal
object must not be
garbage collected while its source signals is non-empty and it has registered event
listeners for its abort
event or its abort algorithms is non-empty.
3.3. Using AbortController
and AbortSignal
objects in
APIs
Any web platform API using promises to represent operations that can be aborted must adhere to the following:
- Accept
AbortSignal
objects through asignal
dictionary member. - Convey that the operation got aborted by rejecting the promise with
AbortSignal
object’s abort reason. - Reject immediately if the
AbortSignal
is already aborted, otherwise: - Use the abort algorithms mechanism to observe changes to the
AbortSignal
object and do so in a manner that does not lead to clashes with other observers.
The method steps for a promise-returning method doAmazingness(options)
could be as follows:
-
Let global be this's relevant global object.
-
Let p be a new promise.
-
If options["
signal
"] member is present, then:-
Let signal be options["
signal
"]. -
If signal is aborted, then reject p with signal’s abort reason and return p.
-
Add the following abort steps to signal:
-
Stop doing amazing things.
-
Reject p with signal’s abort reason.
-
-
-
Run these steps in parallel:
-
Let amazingResult be the result of doing some amazing things.
-
Queue a global task on the amazing task source given global to resolve p with amazingResult.
-
-
Return p.
APIs not using promises should still adhere to the above as much as possible.
4. Nodes
4.1. Introduction to "The DOM"
In its original sense, "The DOM" is an API for accessing and manipulating documents (in particular, HTML and XML documents). In this specification, the term "document" is used for any markup-based resource, ranging from short static documents to long essays or reports with rich multimedia, as well as to fully-fledged interactive applications.
Each such document is represented as a node tree. Some of the nodes in a tree can have children, while others are always leaves.
To illustrate, consider this HTML document:
<!DOCTYPE html> < html class = e > < head >< title > Aliens?</ title ></ head > < body > Why yes.</ body > </ html >
It is represented as follows:
Note that, due to the magic that is HTML parsing, not all ASCII whitespace were turned into Text
nodes, but the general concept is
clear. Markup goes in, a tree of nodes comes out.
The most excellent Live DOM Viewer can be used to explore this matter in more detail.
4.2. Node tree
Nodes are objects that implement Node
. Nodes participate in a tree, which is known as the node tree.
In practice you deal with more specific objects.
Objects that implement Node
also implement an inherited interface: Document
, DocumentType
, DocumentFragment
, Element
, CharacterData
, or Attr
.
Objects that implement DocumentFragment
sometimes implement ShadowRoot
.
Objects that implement Element
also typically implement an inherited interface, such as HTMLAnchorElement
.
Objects that implement CharacterData
also implement an inherited interface: Text
, ProcessingInstruction
, or Comment
.
Objects that implement Text
sometimes implement CDATASection
.
Thus, every node's primary interface is one of: Document
, DocumentType
, DocumentFragment
, ShadowRoot
, Element
or an inherited interface of Element
, Attr
, Text
, CDATASection
, ProcessingInstruction
, or Comment
.
For brevity, this specification refers to an object that implements Node
and an
inherited interface NodeInterface
, as a NodeInterface
node.
A node tree is constrained as follows, expressed as a relationship between a node and its potential children:
Document
-
In tree order:
-
Zero or more
ProcessingInstruction
orComment
nodes. -
Optionally one
DocumentType
node. -
Zero or more
ProcessingInstruction
orComment
nodes. -
Zero or more
ProcessingInstruction
orComment
nodes.
-
DocumentFragment
Element
-
Zero or more
Element
orCharacterData
nodes. DocumentType
CharacterData
Attr
-
No children.
Attr
nodes participate in a tree for historical
reasons; they never have a (non-null) parent or any children and are
therefore alone in a tree.
To determine the length of a node node, run these steps:
-
If node is a
DocumentType
orAttr
node, then return 0. -
If node is a
CharacterData
node, then return node’s data’s length. -
Return the number of node’s children.
A node is considered empty if its length is 0.
4.2.1. Document tree
A document tree is a node tree whose root is a document.
The document element of a document is the element whose parent is that document, if it exists; otherwise null.
Per the node tree constraints, there can be only one such element.
A node is in a document tree if its root is a document.
A node is in a document if it is in a document tree. The term in a document is no longer supposed to be used. It indicates that the standard using it has not been updated to account for shadow trees.
4.2.2. Shadow tree
A shadow tree is a node tree whose root is a shadow root.
A shadow root is always attached to another node tree through its host. A shadow tree is therefore never alone. The node tree of a shadow root’s host is sometimes referred to as the light tree.
A shadow tree’s corresponding light tree can be a shadow tree itself.
A node is connected if its shadow-including root is a document.
4.2.2.1. Slots
A shadow tree contains zero or more elements that are slots.
A slot can only be created through HTML’s slot
element.
A slot has an associated name (a string). Unless stated otherwise it is the empty string.
Use these attribute change steps to update a slot’s name:
-
If element is a slot, localName is
name
, and namespace is null, then:-
If value is oldValue, then return.
-
If value is null and oldValue is the empty string, then return.
-
If value is the empty string and oldValue is null, then return.
-
If value is null or the empty string, then set element’s name to the empty string.
-
Otherwise, set element’s name to value.
-
Run assign slottables for a tree with element’s root.
-
The first slot in a shadow tree, in tree order, whose name is the empty string, is sometimes known as the "default slot".
A slot has an associated assigned nodes (a list of slottables). Unless stated otherwise it is empty.
4.2.2.2. Slottables
Element
and Text
nodes are slottables.
A slottable has an associated name (a string). Unless stated otherwise it is the empty string.
Use these attribute change steps to update a slottable’s name:
-
If localName is
slot
and namespace is null, then:-
If value is oldValue, then return.
-
If value is null and oldValue is the empty string, then return.
-
If value is the empty string and oldValue is null, then return.
-
If value is null or the empty string, then set element’s name to the empty string.
-
Otherwise, set element’s name to value.
-
If element is assigned, then run assign slottables for element’s assigned slot.
-
Run assign a slot for element.
-
A slottable has an associated assigned slot (null or a slot). Unless stated otherwise it is null. A slottable is assigned if its assigned slot is non-null.
A slottable has an associated manual slot assignment (null or a slot). Unless stated otherwise, it is null.
A slottable’s manual slot assignment can be implemented using a weak reference to the slot, because this variable is not directly accessible from script.
4.2.2.3. Finding slots and slottables
To find a slot for a given slottable slottable and an optional open flag (unset unless stated otherwise), run these steps:
-
If slottable’s parent is null, then return null.
-
Let shadow be slottable’s parent’s shadow root.
-
If shadow is null, then return null.
-
If the open flag is set and shadow’s mode is not "
open
", then return null. -
If shadow’s slot assignment is "
manual
", then return the slot in shadow’s descendants whose manually assigned nodes contains slottable, if any; otherwise null. -
Return the first slot in tree order in shadow’s descendants whose name is slottable’s name, if any; otherwise null.
To find slottables for a given slot slot, run these steps:
-
Let result be an empty list.
-
Let root be slot’s root.
-
If root is not a shadow root, then return result.
-
Let host be root’s host.
-
If root’s slot assignment is "
manual
", then:-
Let result be « ».
-
For each slottable slottable of slot’s manually assigned nodes, if slottable’s parent is host, append slottable to result.
-
-
Otherwise, for each slottable child slottable of host, in tree order:
-
Let foundSlot be the result of finding a slot given slottable.
-
If foundSlot is slot, then append slottable to result.
-
-
Return result.
To find flattened slottables for a given slot slot, run these steps:
-
Let result be an empty list.
-
If slot’s root is not a shadow root, then return result.
-
Let slottables be the result of finding slottables given slot.
-
If slottables is the empty list, then append each slottable child of slot, in tree order, to slottables.
-
For each node in slottables:
-
If node is a slot whose root is a shadow root, then:
-
Let temporaryResult be the result of finding flattened slottables given node.
-
Append each slottable in temporaryResult, in order, to result.
-
-
Otherwise, append node to result.
-
-
Return result.
4.2.2.4. Assigning slottables and slots
To assign slottables for a slot slot, run these steps:
-
Let slottables be the result of finding slottables for slot.
-
If slottables and slot’s assigned nodes are not identical, then run signal a slot change for slot.
-
Set slot’s assigned nodes to slottables.
-
For each slottable in slottables, set slottable’s assigned slot to slot.
To assign slottables for a tree, given a node root, run assign slottables for each slot slot in root’s inclusive descendants, in tree order.
To assign a slot, given a slottable slottable, run these steps:
-
Let slot be the result of finding a slot with slottable.
-
If slot is non-null, then run assign slottables for slot.
4.2.2.5. Signaling slot change
Each similar-origin window agent has signal slots (a set of slots), which is initially empty. [HTML]
To signal a slot change, for a slot slot, run these steps:
-
Append slot to slot’s relevant agent’s signal slots.
4.2.3. Mutation algorithms
To ensure pre-insertion validity of a node into a parent before a child, run these steps:
-
If parent is not a
Document
,DocumentFragment
, orElement
node, then throw a "HierarchyRequestError
"DOMException
. -
If node is a host-including inclusive ancestor of parent, then throw a "
HierarchyRequestError
"DOMException
. -
If child is non-null and its parent is not parent, then throw a "
NotFoundError
"DOMException
. -
If node is not a
DocumentFragment
,DocumentType
,Element
, orCharacterData
node, then throw a "HierarchyRequestError
"DOMException
. -
If either node is a
Text
node and parent is a document, or node is a doctype and parent is not a document, then throw a "HierarchyRequestError
"DOMException
. -
If parent is a document, and any of the statements below, switched on the interface node implements, are true, then throw a "
HierarchyRequestError
"DOMException
.DocumentFragment
-
If node has more than one element child or has a
Text
node child.Otherwise, if node has one element child and either parent has an element child, child is a doctype, or child is non-null and a doctype is following child.
Element
-
parent has an element child, child is a doctype, or child is non-null and a doctype is following child.
DocumentType
-
parent has a doctype child, child is non-null and an element is preceding child, or child is null and parent has an element child.
To pre-insert a node into a parent before a child, run these steps:
-
Ensure pre-insertion validity of node into parent before child.
-
Let referenceChild be child.
-
If referenceChild is node, then set referenceChild to node’s next sibling.
-
Insert node into parent before referenceChild.
-
Return node.
Specifications may define insertion steps for all or some nodes. The algorithm is passed insertedNode, as indicated in the insert algorithm below. These steps must not modify the node tree that insertedNode participates in, create browsing contexts, fire events, or otherwise execute JavaScript. These steps may queue tasks to do these things asynchronously, however.
While the insertion steps cannot execute JavaScript (among other things), they will indeed have script-observable consequences. Consider the below example:
const h1 = document. querySelector( 'h1' );
const fragment = new DocumentFragment();
const script = fragment. appendChild( document. createElement( 'script' ));
const style = fragment. appendChild( document. createElement( 'style' ));
script. innerText= 'console.log(getComputedStyle(h1).color)' ; // Logs 'rgb(255, 0, 0)'
style. innerText = 'h1 {color: rgb(255, 0, 0);}' ;
document. body. append( fragment);
The script in the above example logs
because
the following happen in order:
-
The insert algorithm runs, which will insert the
script
andstyle
elements in order.-
The HTML Standard’s insertion steps run for the
script
element; they do nothing. [HTML] -
The HTML Standard’s insertion steps run for the
style
element; they immediately apply its style rules to the document. [HTML] -
The HTML Standard’s post-connection steps run for the
script
element; they run the script, which immediately observes the style rules that were applied in the above step. [HTML]
-
Specifications may also define post-connection steps for all or some nodes. The algorithm is passed connectedNode, as indicated in the insert algorithm below.
The purpose of the post-connection steps is to provide an opportunity for nodes to perform any connection-related operations that modify the node tree that connectedNode participates in, create browsing contexts, or otherwise execute JavaScript. These steps allow a batch of nodes to be inserted atomically with respect to script, with all major side effects occurring after the batch insertions into the node tree is complete. This ensures that all pending node tree insertions completely finish before more insertions can occur.
Specifications may define children changed steps for all or some nodes. The algorithm is passed no argument and is called from insert, remove, and replace data.
To insert a node into a parent before a child, with an optional suppress observers flag, run these steps:
-
Let nodes be node’s children, if node is a
DocumentFragment
node; otherwise « node ». -
Let count be nodes’s size.
-
If count is 0, then return.
-
If node is a
DocumentFragment
node, then:-
Queue a tree mutation record for node with « », nodes, null, and null.
This step intentionally does not pay attention to the suppress observers flag.
-
If child is non-null, then:
-
For each live range whose start node is parent and start offset is greater than child’s index, increase its start offset by count.
-
For each live range whose end node is parent and end offset is greater than child’s index, increase its end offset by count.
-
-
Let previousSibling be child’s previous sibling or parent’s last child if child is null.
-
For each node in nodes, in tree order:
-
Adopt node into parent’s node document.
-
Otherwise, insert node into parent’s children before child’s index.
-
If parent is a shadow host whose shadow root’s slot assignment is "
named
" and node is a slottable, then assign a slot for node. -
If parent’s root is a shadow root, and parent is a slot whose assigned nodes is the empty list, then run signal a slot change for parent.
-
Run assign slottables for a tree with node’s root.
-
For each shadow-including inclusive descendant inclusiveDescendant of node, in shadow-including tree order:
-
Run the insertion steps with inclusiveDescendant.
-
If inclusiveDescendant is connected, then:
-
If inclusiveDescendant is custom, then enqueue a custom element callback reaction with inclusiveDescendant, callback name "
connectedCallback
", and an empty argument list. -
Otherwise, try to upgrade inclusiveDescendant.
If this successfully upgrades inclusiveDescendant, its
connectedCallback
will be enqueued automatically during the upgrade an element algorithm.
-
-
-
-
If suppress observers flag is unset, then queue a tree mutation record for parent with nodes, « », previousSibling, and child.
-
Run the children changed steps for parent.
-
Let staticNodeList be a list of nodes, initially « ».
We collect all nodes before calling the post-connection steps on any one of them, instead of calling the post-connection steps while we’re traversing the node tree. This is because the post-connection steps can modify the tree’s structure, making live traversal unsafe, possibly leading to the post-connection steps being called multiple times on the same node.
-
For each node of nodes, in tree order:
-
For each shadow-including inclusive descendant inclusiveDescendant of node, in shadow-including tree order, append inclusiveDescendant to staticNodeList.
-
-
For each node of staticNodeList, if node is connected, then run the post-connection steps with node.
To append a node to a parent, pre-insert node into parent before null.
To replace a child with node within a parent, run these steps:
-
If parent is not a
Document
,DocumentFragment
, orElement
node, then throw a "HierarchyRequestError
"DOMException
. -
If node is a host-including inclusive ancestor of parent, then throw a "
HierarchyRequestError
"DOMException
. -
If child’s parent is not parent, then throw a "
NotFoundError
"DOMException
. -
If node is not a
DocumentFragment
,DocumentType
,Element
, orCharacterData
node, then throw a "HierarchyRequestError
"DOMException
. -
If either node is a
Text
node and parent is a document, or node is a doctype and parent is not a document, then throw a "HierarchyRequestError
"DOMException
. -
If parent is a document, and any of the statements below, switched on the interface node implements, are true, then throw a "
HierarchyRequestError
"DOMException
.DocumentFragment
-
If node has more than one element child or has a
Text
node child.Otherwise, if node has one element child and either parent has an element child that is not child or a doctype is following child.
Element
-
parent has an element child that is not child or a doctype is following child.
DocumentType
-
parent has a doctype child that is not child, or an element is preceding child.
The above statements differ from the pre-insert algorithm.
-
Let referenceChild be child’s next sibling.
-
If referenceChild is node, then set referenceChild to node’s next sibling.
-
Let previousSibling be child’s previous sibling.
-
Let removedNodes be the empty set.
-
If child’s parent is non-null, then:
-
Set removedNodes to « child ».
-
Remove child with the suppress observers flag set.
The above can only be false if child is node.
-
-
Let nodes be node’s children if node is a
DocumentFragment
node; otherwise « node ». -
Insert node into parent before referenceChild with the suppress observers flag set.
-
Queue a tree mutation record for parent with nodes, removedNodes, previousSibling, and referenceChild.
-
Return child.
To replace all with a node within a parent, run these steps:
-
Let removedNodes be parent’s children.
-
Let addedNodes be the empty set.
-
If node is a
DocumentFragment
node, then set addedNodes to node’s children. -
Otherwise, if node is non-null, set addedNodes to « node ».
-
Remove all parent’s children, in tree order, with the suppress observers flag set.
-
If node is non-null, then insert node into parent before null with the suppress observers flag set.
-
If either addedNodes or removedNodes is not empty, then queue a tree mutation record for parent with addedNodes, removedNodes, null, and null.
This algorithm does not make any checks with regards to the node tree constraints. Specification authors need to use it wisely.
To pre-remove a child from a parent, run these steps:
-
If child’s parent is not parent, then throw a "
NotFoundError
"DOMException
. -
Remove child.
-
Return child.
Specifications may define removing steps for all or some nodes. The algorithm is passed a node removedNode and a node-or-null oldParent, as indicated in the remove algorithm below.
To remove a node node, with an optional suppress observers flag, run these steps:
-
Let parent be node’s parent.
-
Assert: parent is non-null.
-
Let index be node’s index.
-
For each live range whose start node is an inclusive descendant of node, set its start to (parent, index).
-
For each live range whose end node is an inclusive descendant of node, set its end to (parent, index).
-
For each live range whose start node is parent and start offset is greater than index, decrease its start offset by 1.
-
For each live range whose end node is parent and end offset is greater than index, decrease its end offset by 1.
-
For each
NodeIterator
object iterator whose root’s node document is node’s node document, run theNodeIterator
pre-removing steps given node and iterator. -
Let oldPreviousSibling be node’s previous sibling.
-
Let oldNextSibling be node’s next sibling.
-
If node is assigned, then run assign slottables for node’s assigned slot.
-
If parent’s root is a shadow root, and parent is a slot whose assigned nodes is the empty list, then run signal a slot change for parent.
-
If node has an inclusive descendant that is a slot, then:
-
Run assign slottables for a tree with parent’s root.
-
Run assign slottables for a tree with node.
-
-
Run the removing steps with node and parent.
-
Let isParentConnected be parent’s connected.
-
If node is custom and isParentConnected is true, then enqueue a custom element callback reaction with node, callback name "
disconnectedCallback
", and an empty argument list.It is intentional for now that custom elements do not get parent passed. This might change in the future if there is a need.
-
For each shadow-including descendant descendant of node, in shadow-including tree order, then:
-
Run the removing steps with descendant and null.
-
If descendant is custom and isParentConnected is true, then enqueue a custom element callback reaction with descendant, callback name "
disconnectedCallback
", and an empty argument list.
-
-
For each inclusive ancestor inclusiveAncestor of parent, and then for each registered of inclusiveAncestor’s registered observer list, if registered’s options["
subtree
"] is true, then append a new transient registered observer whose observer is registered’s observer, options is registered’s options, and source is registered to node’s registered observer list. -
If suppress observers flag is unset, then queue a tree mutation record for parent with « », « node », oldPreviousSibling, and oldNextSibling.
-
Run the children changed steps for parent.
4.2.4. Mixin NonElementParentNode
Web compatibility prevents the getElementById()
method from being exposed on elements (and therefore on ParentNode
).
interface mixin {
NonElementParentNode Element ?getElementById (DOMString ); };
elementId Document includes NonElementParentNode ;DocumentFragment includes NonElementParentNode ;
node . getElementById(elementId)
-
Returns the first element within node’s descendants whose ID is elementId.
The getElementById(elementId)
method steps are to return the first element, in tree order, within this’s descendants, whose ID is elementId;
otherwise, if there is no such element, null.
4.2.5. Mixin DocumentOrShadowRoot
interface mixin { };
DocumentOrShadowRoot Document includes DocumentOrShadowRoot ;ShadowRoot includes DocumentOrShadowRoot ;
The DocumentOrShadowRoot
mixin is expected to be used by other
standards that want to define APIs shared between documents and shadow roots.
4.2.6. Mixin ParentNode
To convert nodes into a node, given nodes and document, run these steps:
-
Let node be null.
-
Replace each string in nodes with a new
Text
node whose data is the string and node document is document. -
If nodes contains one node, then set node to nodes[0].
-
Otherwise, set node to a new
DocumentFragment
node whose node document is document, and then append each node in nodes, if any, to it. -
Return node.
interface mixin { [
ParentNode SameObject ]readonly attribute HTMLCollection children ;readonly attribute Element ?firstElementChild ;readonly attribute Element ?lastElementChild ;readonly attribute unsigned long childElementCount ; [CEReactions ,Unscopable ]undefined prepend ((Node or DOMString )...); [
nodes CEReactions ,Unscopable ]undefined append ((Node or DOMString )...); [
nodes CEReactions ,Unscopable ]undefined replaceChildren ((Node or DOMString )...);
nodes Element ?querySelector (DOMString ); [
selectors NewObject ]NodeList querySelectorAll (DOMString ); };
selectors Document includes ParentNode ;DocumentFragment includes ParentNode ;Element includes ParentNode ;
collection = node .
children
- Returns the child elements.
element = node .
firstElementChild
- Returns the first child that is an element; otherwise null.
element = node .
lastElementChild
- Returns the last child that is an element; otherwise null.
node . prepend(nodes)
-
Inserts nodes before the first child of node, while replacing strings in nodes with equivalent
Text
nodes.Throws a "
HierarchyRequestError
"DOMException
if the constraints of the node tree are violated. node . append(nodes)
-
Inserts nodes after the last child of node, while replacing strings in nodes with equivalent
Text
nodes.Throws a "
HierarchyRequestError
"DOMException
if the constraints of the node tree are violated. node . replaceChildren(nodes)
-
Replace all children of node with nodes, while replacing strings in nodes with equivalent
Text
nodes.Throws a "
HierarchyRequestError
"DOMException
if the constraints of the node tree are violated. node . querySelector(selectors)
-
Returns the first element that is a descendant of node that matches selectors.
node . querySelectorAll(selectors)
-
Returns all element descendants of node that match selectors.
The children
getter steps are to return an HTMLCollection
collection rooted at this matching only element children.
The firstElementChild
getter steps are to return
the first child that is an element; otherwise null.
The lastElementChild
getter steps are to return
the last child that is an element; otherwise null.
The childElementCount
getter steps are to return
the number of children of this that are elements.
The prepend(nodes)
method steps are:
-
Let node be the result of converting nodes into a node given nodes and this’s node document.
-
Pre-insert node into this before this’s first child.
The append(nodes)
method steps are:
-
Let node be the result of converting nodes into a node given nodes and this’s node document.
The replaceChildren(nodes)
method steps
are:
-
Let node be the result of converting nodes into a node given nodes and this’s node document.
-
Ensure pre-insertion validity of node into this before null.
-
Replace all with node within this.
The querySelector(selectors)
method
steps are to return the first result of running scope-match a selectors string selectors against this, if the result is not an empty list; otherwise null.
The querySelectorAll(selectors)
method
steps are to return the static result of running scope-match a selectors string selectors against this.
4.2.7. Mixin NonDocumentTypeChildNode
Web compatibility prevents the previousElementSibling
and nextElementSibling
attributes from being exposed on doctypes (and therefore on ChildNode
).
interface mixin {
NonDocumentTypeChildNode readonly attribute Element ?previousElementSibling ;readonly attribute Element ?nextElementSibling ; };Element includes NonDocumentTypeChildNode ;CharacterData includes NonDocumentTypeChildNode ;
element = node .
previousElementSibling
- Returns the first preceding sibling that is an element; otherwise null.
element = node .
nextElementSibling
- Returns the first following sibling that is an element; otherwise null.
The previousElementSibling
getter
steps are to return the first preceding sibling that is an element; otherwise null.
The nextElementSibling
getter
steps are to return the first following sibling that is an element; otherwise null.
4.2.8. Mixin ChildNode
interface mixin { [
ChildNode CEReactions ,Unscopable ]undefined before ((Node or DOMString )...); [
nodes CEReactions ,Unscopable ]undefined after ((Node or DOMString )...); [
nodes CEReactions ,Unscopable ]undefined replaceWith ((Node or DOMString )...); [
nodes CEReactions ,Unscopable ]undefined remove (); };DocumentType includes ChildNode ;Element includes ChildNode ;CharacterData includes ChildNode ;
node .
before(...nodes)
-
Inserts nodes just before node, while replacing strings in nodes with equivalent
Text
nodes.Throws a "
HierarchyRequestError
"DOMException
if the constraints of the node tree are violated. node .
after(...nodes)
-
Inserts nodes just after node, while replacing strings in nodes with equivalent
Text
nodes.Throws a "
HierarchyRequestError
"DOMException
if the constraints of the node tree are violated. node .
replaceWith(...nodes)
-
Replaces node with nodes, while replacing strings in nodes with equivalent
Text
nodes.Throws a "
HierarchyRequestError
"DOMException
if the constraints of the node tree are violated. node .
remove()
- Removes node.
The before(nodes)
method steps are:
-
If parent is null, then return.
-
Let viablePreviousSibling be this’s first preceding sibling not in nodes; otherwise null.
-
Let node be the result of converting nodes into a node, given nodes and this’s node document.
-
If viablePreviousSibling is null, then set it to parent’s first child; otherwise to viablePreviousSibling’s next sibling.
-
Pre-insert node into parent before viablePreviousSibling.
The after(nodes)
method steps are:
-
If parent is null, then return.
-
Let viableNextSibling be this’s first following sibling not in nodes; otherwise null.
-
Let node be the result of converting nodes into a node, given nodes and this’s node document.
-
Pre-insert node into parent before viableNextSibling.
The replaceWith(nodes)
method steps are:
-
If parent is null, then return.
-
Let viableNextSibling be this’s first following sibling not in nodes; otherwise null.
-
Let node be the result of converting nodes into a node, given nodes and this’s node document.
-
If this’s parent is parent, replace this with node within parent.
This could have been inserted into node.
-
Otherwise, pre-insert node into parent before viableNextSibling.
The remove()
method steps are:
4.2.9. Mixin Slottable
interface mixin {
Slottable readonly attribute HTMLSlotElement ?assignedSlot ; };Element includes Slottable ;Text includes Slottable ;
The assignedSlot
getter steps are to return the result of find a slot given this and with the open flag set.
4.2.10. Old-style collections: NodeList
and HTMLCollection
A collection is an object that represents a list of nodes. A collection can be either live or static. Unless otherwise stated, a collection must be live.
If a collection is live, then the attributes and methods on that object must operate on the actual underlying data, not a snapshot of the data.
When a collection is created, a filter and a root are associated with it.
The collection then represents a view of the subtree rooted at the collection’s root, containing only nodes that match the given filter. The view is linear. In the absence of specific requirements to the contrary, the nodes within the collection must be sorted in tree order.
4.2.10.1. Interface NodeList
A NodeList
object is a collection of nodes.
[Exposed =Window ]interface {
NodeList getter Node ?item (unsigned long );
index readonly attribute unsigned long length ;iterable <Node >; };
- collection .
length
- Returns the number of nodes in the collection.
- element = collection .
item(index)
- element = collection[index]
- Returns the node with index index from the collection. The nodes are sorted in tree order.
The object’s supported property indices are the numbers in the range zero to one less than the number of nodes represented by the collection. If there are no such elements, then there are no supported property indices.
The length
attribute must return the number of nodes represented by the collection.
The item(index)
method must return the indexth node in the collection. If there is no indexth node in the collection, then the method must
return null.
4.2.10.2. Interface HTMLCollection
[Exposed =Window ,LegacyUnenumerableNamedProperties ]interface {
HTMLCollection readonly attribute unsigned long length ;getter Element ?item (unsigned long );
index getter Element ?(
namedItem DOMString ); };
name
An HTMLCollection
object is a collection of elements.
HTMLCollection
is a historical artifact we cannot rid the web of.
While developers are of course welcome to keep using it, new API standard designers ought not to use
it (use sequence<T>
in IDL instead).
- collection .
length
- Returns the number of elements in the collection.
- element = collection .
item(index)
- element = collection[index]
- Returns the element with index index from the collection. The elements are sorted in tree order.
- element = collection .
namedItem(name)
- element = collection[name]
- Returns the first element with ID or name name from the collection.
The object’s supported property indices are the numbers in the range zero to one less than the number of elements represented by the collection. If there are no such elements, then there are no supported property indices.
The length
getter steps are to return the
number of nodes represented by the collection.
The item(index)
method steps are to
return the indexth element in the collection. If there
is no indexth element in the collection, then the method
must return null.
The supported property names are the values from the list returned by these steps:
-
Let result be an empty list.
-
For each element represented by the collection, in tree order:
-
If element has an ID which is not in result, append element’s ID to result.
-
If element is in the HTML namespace and has a
name
attribute whose value is neither the empty string nor is in result, append element’sname
attribute value to result.
-
-
Return result.
The namedItem(key)
method steps are:
-
If key is the empty string, return null.
-
Return the first element in the collection for which at least one of the following is true:
- it has an ID which is key;
- it is in the HTML namespace and has a
name
attribute whose value is key;
or null if there is no such element.
4.3. Mutation observers
Each similar-origin window agent has a mutation observer microtask queued (a boolean), which is initially false. [HTML]
Each similar-origin window agent also has pending mutation observers (a set of zero or more MutationObserver
objects), which is initially empty.
To queue a mutation observer microtask, run these steps:
-
If the surrounding agent’s mutation observer microtask queued is true, then return.
-
Set the surrounding agent’s mutation observer microtask queued to true.
To notify mutation observers, run these steps:
-
Set the surrounding agent’s mutation observer microtask queued to false.
-
Let notifySet be a clone of the surrounding agent’s pending mutation observers.
-
Let signalSet be a clone of the surrounding agent’s signal slots.
-
Empty the surrounding agent’s signal slots.
-
For each mo of notifySet:
-
Let records be a clone of mo’s record queue.
-
Empty mo’s record queue.
-
For each node of mo’s node list, remove all transient registered observers whose observer is mo from node’s registered observer list.
-
If records is not empty, then invoke mo’s callback with « records, mo » and "
report
", and with callback this value mo.
-
-
For each slot of signalSet, fire an event named
slotchange
, with itsbubbles
attribute set to true, at slot.
Each node has a registered observer list (a list of zero or more registered observers), which is initially empty.
A registered observer consists of an observer (a MutationObserver
object) and options (a MutationObserverInit
dictionary).
A transient registered observer is a registered observer that also consists of a source (a registered observer).
Transient registered observers are used to track mutations within
a given node’s descendants after node has been removed so
they do not get lost when subtree
is set to true on node’s parent.
4.3.1. Interface MutationObserver
[Exposed =Window ]interface {
MutationObserver constructor (MutationCallback );
callback undefined observe (Node ,
target optional MutationObserverInit = {});
options undefined disconnect ();sequence <MutationRecord >takeRecords (); };callback =
MutationCallback undefined (sequence <MutationRecord >,
mutations MutationObserver );
observer dictionary {
MutationObserverInit boolean =
childList false ;boolean ;
attributes boolean ;
characterData boolean =
subtree false ;boolean ;
attributeOldValue boolean ;
characterDataOldValue sequence <DOMString >; };
attributeFilter
A MutationObserver
object can be used to observe mutations to the tree of nodes.
Each MutationObserver
object has these associated concepts:
- A callback set on creation.
- A node list (a list of weak references to nodes), which is initially empty.
- A record queue (a queue of
zero or more
MutationRecord
objects), which is initially empty.
observer = new
MutationObserver(callback)
- Constructs a
MutationObserver
object and sets its callback to callback. The callback is invoked with a list ofMutationRecord
objects as first argument and the constructedMutationObserver
object as second argument. It is invoked after nodes registered with theobserve()
method, are mutated. observer .
observe(target, options)
-
Instructs the user agent to observe a given target (a node) and report any mutations based on
the criteria given by options (an object).
The options argument allows for setting mutation observation options via object members. These are the object members that can be used:
childList
- Set to true if mutations to target’s children are to be observed.
attributes
- Set to true if mutations to target’s attributes are to be observed. Can be omitted if
attributeOldValue
orattributeFilter
is specified. characterData
- Set to true if mutations to target’s data are to be observed. Can be omitted if
characterDataOldValue
is specified. subtree
- Set to true if mutations to not just target, but also target’s descendants are to be observed.
attributeOldValue
- Set to true if
attributes
is true or omitted and target’s attribute value before the mutation needs to be recorded. characterDataOldValue
- Set to true if
characterData
is set to true or omitted and target’s data before the mutation needs to be recorded. attributeFilter
- Set to a list of attribute local names (without namespace) if not all attribute mutations need to be
observed and
attributes
is true or omitted.
observer .
disconnect()
- Stops observer from observing any mutations. Until the
observe()
method is used again, observer’s callback will not be invoked. observer .
takeRecords()
- Empties the record queue and returns what was in there.
The new MutationObserver(callback)
constructor steps are to set this’s callback to callback.
The observe(target, options)
method steps are:
-
If either options["
attributeOldValue
"] or options["attributeFilter
"] exists, and options["attributes
"] does not exist, then set options["attributes
"] to true. -
If options["
characterDataOldValue
"] exists and options["characterData
"] does not exist, then set options["characterData
"] to true. -
If none of options["
childList
"], options["attributes
"], and options["characterData
"] is true, then throw aTypeError
. -
If options["
attributeOldValue
"] is true and options["attributes
"] is false, then throw aTypeError
. -
If options["
attributeFilter
"] is present and options["attributes
"] is false, then throw aTypeError
. -
If options["
characterDataOldValue
"] is true and options["characterData
"] is false, then throw aTypeError
. -
For each registered of target’s registered observer list, if registered’s observer is this:
-
For each node of this’s node list, remove all transient registered observers whose source is registered from node’s registered observer list.
-
Set registered’s options to options.
-
-
Otherwise:
-
Append a new registered observer whose observer is this and options is options to target’s registered observer list.
-
The disconnect()
method steps are:
-
For each node of this’s node list, remove any registered observer from node’s registered observer list for which this is the observer.
The takeRecords()
method steps are:
-
Let records be a clone of this’s record queue.
-
Return records.
4.3.2. Queuing a mutation record
To queue a mutation record of type for target with name, namespace, oldValue, addedNodes, removedNodes, previousSibling, and nextSibling, run these steps:
-
Let interestedObservers be an empty map.
-
Let nodes be the inclusive ancestors of target.
-
For each node in nodes, and then for each registered of node’s registered observer list:
-
Let options be registered’s options.
-
If none of the following are true
- node is not target and options["
subtree
"] is false - type is "
attributes
" and options["attributes
"] either does not exist or is false - type is "
attributes
", options["attributeFilter
"] exists, and options["attributeFilter
"] does not contain name or namespace is non-null - type is "
characterData
" and options["characterData
"] either does not exist or is false - type is "
childList
" and options["childList
"] is false
then:
-
Let mo be registered’s observer.
-
If interestedObservers[mo] does not exist, then set interestedObservers[mo] to null.
-
If either type is "
attributes
" and options["attributeOldValue
"] is true, or type is "characterData
" and options["characterDataOldValue
"] is true, then set interestedObservers[mo] to oldValue.
- node is not target and options["
-
-
For each observer → mappedOldValue of interestedObservers:
-
Let record be a new
MutationRecord
object with itstype
set to type,target
set to target,attributeName
set to name,attributeNamespace
set to namespace,oldValue
set to mappedOldValue,addedNodes
set to addedNodes,removedNodes
set to removedNodes,previousSibling
set to previousSibling, andnextSibling
set to nextSibling. -
Enqueue record to observer’s record queue.
-
Append observer to the surrounding agent’s pending mutation observers.
-
To queue a tree mutation record for target with addedNodes, removedNodes, previousSibling, and nextSibling, run these steps:
-
Assert: either addedNodes or removedNodes is not empty.
-
Queue a mutation record of "
childList
" for target with null, null, null, addedNodes, removedNodes, previousSibling, and nextSibling.
4.3.3. Interface MutationRecord
[Exposed =Window ]interface {
MutationRecord readonly attribute DOMString type ; [SameObject ]readonly attribute Node target ; [SameObject ]readonly attribute NodeList addedNodes ; [SameObject ]readonly attribute NodeList removedNodes ;readonly attribute Node ?previousSibling ;readonly attribute Node ?nextSibling ;readonly attribute DOMString ?attributeName ;readonly attribute DOMString ?attributeNamespace ;readonly attribute DOMString ?oldValue ; };
record .
type
- Returns "
attributes
" if it was an attribute mutation. "characterData
" if it was a mutation to aCharacterData
node. And "childList
" if it was a mutation to the tree of nodes. record .
target
- Returns the node the mutation
affected, depending on the
type
. For "attributes
", it is the element whose attribute changed. For "characterData
", it is theCharacterData
node. For "childList
", it is the node whose children changed. record .
addedNodes
record .
removedNodes
- Return the nodes added and removed respectively.
record .
previousSibling
record .
nextSibling
- Return the previous and next sibling respectively of the added or removed nodes; otherwise null.
record .
attributeName
- Returns the local name of the changed attribute; otherwise null.
record .
attributeNamespace
- Returns the namespace of the changed attribute; otherwise null.
record .
oldValue
- The return value depends on
type
. For "attributes
", it is the value of the changed attribute before the change. For "characterData
", it is the data of the changed node before the change. For "childList
", it is null.
The type
, target
, addedNodes
, removedNodes
, previousSibling
, nextSibling
, attributeName
, attributeNamespace
, and oldValue
attributes must return the values they were
initialized to.
4.4. Interface Node
[Exposed =Window ]interface :
Node EventTarget {const unsigned short ELEMENT_NODE = 1;const unsigned short ATTRIBUTE_NODE = 2;const unsigned short TEXT_NODE = 3;const unsigned short CDATA_SECTION_NODE = 4;const unsigned short = 5; // legacy
ENTITY_REFERENCE_NODE const unsigned short = 6; // legacy
ENTITY_NODE const unsigned short PROCESSING_INSTRUCTION_NODE = 7;const unsigned short COMMENT_NODE = 8;const unsigned short DOCUMENT_NODE = 9;const unsigned short DOCUMENT_TYPE_NODE = 10;const unsigned short DOCUMENT_FRAGMENT_NODE = 11;const unsigned short = 12; // legacy
NOTATION_NODE readonly attribute unsigned short nodeType ;readonly attribute DOMString nodeName ;readonly attribute USVString baseURI ;readonly attribute boolean isConnected ;readonly attribute Document ?ownerDocument ;Node getRootNode (optional GetRootNodeOptions = {});
options readonly attribute Node ?parentNode ;readonly attribute Element ?parentElement ;boolean hasChildNodes (); [SameObject ]readonly attribute NodeList childNodes ;readonly attribute Node ?firstChild ;readonly attribute Node ?lastChild ;readonly attribute Node ?previousSibling ;readonly attribute Node ?nextSibling ; [CEReactions ]attribute DOMString ?nodeValue ; [CEReactions ]attribute DOMString ?textContent ; [CEReactions ]undefined normalize (); [CEReactions ,NewObject ]Node cloneNode (optional boolean =
deep false );boolean isEqualNode (Node ?);
otherNode boolean isSameNode (Node ?); // legacy alias of ===
otherNode const unsigned short DOCUMENT_POSITION_DISCONNECTED = 0x01;const unsigned short DOCUMENT_POSITION_PRECEDING = 0x02;const unsigned short DOCUMENT_POSITION_FOLLOWING = 0x04;const unsigned short DOCUMENT_POSITION_CONTAINS = 0x08;const unsigned short DOCUMENT_POSITION_CONTAINED_BY = 0x10;const unsigned short DOCUMENT_POSITION_IMPLEMENTATION_SPECIFIC = 0x20;unsigned short compareDocumentPosition (Node );
other boolean contains (Node ?);
other DOMString ?lookupPrefix (DOMString ?);
namespace DOMString ?lookupNamespaceURI (DOMString ?);
prefix boolean isDefaultNamespace (DOMString ?); [
namespace CEReactions ]Node insertBefore (Node ,
node Node ?); [
child CEReactions ]Node appendChild (Node ); [
node CEReactions ]Node replaceChild (Node ,
node Node ); [
child CEReactions ]Node removeChild (Node ); };
child dictionary {
GetRootNodeOptions boolean =
composed false ; };
Node
is an abstract interface that is used by all nodes. You cannot
get a direct instance of it.
Each node has an associated node document, set upon creation, that is a document.
A node’s node document can be changed by the adopt algorithm.
A node’s get the parent algorithm, given an event, returns the node’s assigned slot, if node is assigned; otherwise node’s parent.
Each node also has a registered observer list.
node .
nodeType
-
Returns a number appropriate for the type of node, as follows:
Element
(1).Node
.ELEMENT_NODE
Attr
(2).Node
.ATTRIBUTE_NODE
- An exclusive
Text
node
(3).Node
.TEXT_NODE
CDATASection
(4).Node
.CDATA_SECTION_NODE
ProcessingInstruction
(7).Node
.PROCESSING_INSTRUCTION_NODE
Comment
(8).Node
.COMMENT_NODE
Document
(9).Node
.DOCUMENT_NODE
DocumentType
(10).Node
.DOCUMENT_TYPE_NODE
DocumentFragment
(11).Node
.DOCUMENT_FRAGMENT_NODE
node .
nodeName
-
Returns a string appropriate for the type of node, as follows:
Element
- Its HTML-uppercased qualified name.
Attr
- Its qualified name.
- An exclusive
Text
node - "
#text
". CDATASection
- "
#cdata-section
". ProcessingInstruction
- Its target.
Comment
- "
#comment
". Document
- "
#document
". DocumentType
- Its name.
DocumentFragment
- "
#document-fragment
".
The nodeType
getter steps are to return the first matching
statement, switching on the interface this implements:
Element
ELEMENT_NODE
(1)Attr
ATTRIBUTE_NODE
(2);- An exclusive
Text
node TEXT_NODE
(3);CDATASection
CDATA_SECTION_NODE
(4);ProcessingInstruction
PROCESSING_INSTRUCTION_NODE
(7);Comment
COMMENT_NODE
(8);Document
DOCUMENT_NODE
(9);DocumentType
DOCUMENT_TYPE_NODE
(10);DocumentFragment
DOCUMENT_FRAGMENT_NODE
(11).
The nodeName
getter steps are to return the first matching
statement, switching on the interface this implements:
Element
- Its HTML-uppercased qualified name.
Attr
- Its qualified name.
- An exclusive
Text
node - "
#text
". CDATASection
- "
#cdata-section
". ProcessingInstruction
- Its target.
Comment
- "
#comment
". Document
- "
#document
". DocumentType
- Its name.
DocumentFragment
- "
#document-fragment
".
node .
baseURI
- Returns node’s node document’s document base URL.
The baseURI
getter steps are to return this’s node document’s document base URL, serialized.
node .
isConnected
-
Returns true if node is connected; otherwise false.
node .
ownerDocument
- Returns the node document. Returns null for documents.
node .
getRootNode()
- Returns node’s root.
node . getRootNode({ composed:true })
- Returns node’s shadow-including root.
node .
parentNode
- Returns the parent.
node .
parentElement
- Returns the parent element.
node .
hasChildNodes()
- Returns whether node has children.
node .
childNodes
- Returns the children.
node .
firstChild
- Returns the first child.
node .
lastChild
- Returns the last child.
node .
previousSibling
- Returns the previous sibling.
node .
nextSibling
- Returns the next sibling.
The isConnected
getter steps are to return true,
if this is connected; otherwise false.
The ownerDocument
getter steps are to return null,
if this is a document; otherwise this’s node document.
The node document of a document is that document itself. All nodes have a node document at all times.
The getRootNode(options)
method steps are to
return this’s shadow-including root if options["composed
"] is true; otherwise this’s root.
The parentNode
getter steps are to return this’s parent.
The parentElement
getter steps are to return this’s parent element.
The hasChildNodes()
method steps are to return true if this has children; otherwise false.
The childNodes
getter steps are to return a NodeList
rooted at this matching only children.
The firstChild
getter steps are to return this’s first child.
The lastChild
getter steps are to return this’s last child.
The previousSibling
getter steps are to return this’s previous sibling.
The nextSibling
getter steps are to return this’s next sibling.
The nodeValue
getter steps are to return the following, switching
on the interface this implements:
Attr
- this’s value.
CharacterData
- this’s data.
- Otherwise
- Null.
The nodeValue
setter steps are to, if the given value is null, act as if it was the
empty string instead, and then do as described below, switching on the interface this implements:
Attr
-
Set an existing attribute value with this and the given value.
CharacterData
-
Replace data with node this, offset 0, count this’s length, and data the given value.
- Otherwise
-
Do nothing.
To get text content with a node node, return the following, switching on the interface node implements:
DocumentFragment
Element
- The descendant text content of node.
Attr
- node’s value.
CharacterData
- node’s data.
- Otherwise
- Null.
The textContent
getter steps are to
return the result of running get text content with this.
To string replace all with a string string within a node parent, run these steps:
-
Let node be null.
-
If string is not the empty string, then set node to a new
Text
node whose data is string and node document is parent’s node document. -
Replace all with node within parent.
To set text content with a node node and a string value, do as defined below, switching on the interface node implements:
DocumentFragment
Element
-
String replace all with value within node.
Attr
-
Set an existing attribute value with node and value.
CharacterData
-
Replace data with node node, offset 0, count node’s length, and data value.
- Otherwise
-
Do nothing.
The textContent
setter steps are to, if the given value is null, act as if it was the
empty string instead, and then run set text content with this and the given value.
node .
normalize()
- Removes empty exclusive
Text
nodes and concatenates the data of remaining contiguous exclusiveText
nodes into the first of their nodes.
The normalize()
method steps are to run these steps for
each descendant exclusive Text
node node of this:
- Let length be node’s length.
- If length is zero, then remove node and continue with the
next exclusive
Text
node, if any. - Let data be the concatenation of the data of node’s contiguous exclusive
Text
nodes (excluding itself), in tree order. - Replace data with node node, offset length, count 0, and data data.
- Let currentNode be node’s next sibling.
-
While currentNode is an exclusive
Text
node:-
For each live range whose start node is currentNode, add length to its start offset and set its start node to node.
-
For each live range whose end node is currentNode, add length to its end offset and set its end node to node.
-
For each live range whose start node is currentNode’s parent and start offset is currentNode’s index, set its start node to node and its start offset to length.
-
For each live range whose end node is currentNode’s parent and end offset is currentNode’s index, set its end node to node and its end offset to length.
-
Add currentNode’s length to length.
-
Set currentNode to its next sibling.
-
- Remove node’s contiguous exclusive
Text
nodes (excluding itself), in tree order.
node . cloneNode([deep = false])
- Returns a copy of node. If deep is true, the copy also includes the node’s descendants.
node .
isEqualNode(otherNode)
- Returns whether node and otherNode have the same properties.
Specifications may define cloning steps for all or some nodes. The algorithm is passed copy, node, document, and an optional clone children flag, as indicated in the clone algorithm.
HTML defines cloning steps for script
and input
elements. SVG ought to do the same for its script
elements, but does not call this out
at the moment.
To clone a node, with an optional document and clone children flag, run these steps:
-
If document is not given, let document be node’s node document.
-
If node is an element, then:
-
Let copy be the result of creating an element, given document, node’s local name, node’s namespace, node’s namespace prefix, and node’s
is
value, with the synchronous custom elements flag unset. -
For each attribute in node’s attribute list:
-
-
Otherwise, let copy be a node that implements the same interfaces as node, and fulfills these additional requirements, switching on the interface node implements:
Document
-
Set copy’s encoding, content type, URL, origin, type, and mode to those of node.
DocumentType
Attr
-
Set copy’s namespace, namespace prefix, local name, and value to those of node.
Text
Comment
-
Set copy’s data to that of node.
ProcessingInstruction
- Otherwise
-
Do nothing.
-
Set copy’s node document and document to copy, if copy is a document, and set copy’s node document to document otherwise.
-
Run any cloning steps defined for node in other applicable specifications and pass copy, node, document, and the clone children flag if set, as parameters.
-
If the clone children flag is set, then for each child child of node, in tree order: append the result of cloning child with document and the clone children flag set, to copy.
-
If node is a shadow host whose shadow root’s clonable is true:
-
Assert: copy is not a shadow host.
-
Run attach a shadow root with copy, node’s shadow root’s mode, true, node’s shadow root’s serializable, node’s shadow root’s delegates focus, and node’s shadow root’s slot assignment.
-
Set copy’s shadow root’s declarative to node’s shadow root’s declarative.
-
For each child child of node’s shadow root, in tree order: append the result of cloning child with document and the clone children flag set, to copy’s shadow root.
-
-
Return copy.
The cloneNode(deep)
method steps are:
-
If this is a shadow root, then throw a "
NotSupportedError
"DOMException
. -
Return a clone of this, with the clone children flag set if deep is true.
A node A equals a node B if all of the following conditions are true:
-
A and B implement the same interfaces.
-
The following are equal, switching on the interface A implements:
DocumentType
- Its name, public ID, and system ID.
Element
- Its namespace, namespace prefix, local name, and its attribute list’s size.
Attr
- Its namespace, local name, and value.
ProcessingInstruction
- Its target and data.
Text
Comment
- Its data.
- Otherwise
- —
-
If A is an element, each attribute in its attribute list has an attribute that equals an attribute in B’s attribute list.
-
A and B have the same number of children.
-
Each child of A equals the child of B at the identical index.
The isEqualNode(otherNode)
method steps are to
return true if otherNode is non-null and this equals otherNode; otherwise false.
The isSameNode(otherNode)
method steps are to
return true if otherNode is this; otherwise false.
node .
compareDocumentPosition(other)
-
Returns a bitmask indicating the position of other relative to node. These are the bits that can be set:
(1)Node
.DOCUMENT_POSITION_DISCONNECTED
- Set when node and other are not in the same tree.
(2)Node
.DOCUMENT_POSITION_PRECEDING
- Set when other is preceding node.
(4)Node
.DOCUMENT_POSITION_FOLLOWING
- Set when other is following node.
(8)Node
.DOCUMENT_POSITION_CONTAINS
- Set when other is an ancestor of node.
(16, 10 in hexadecimal)Node
.DOCUMENT_POSITION_CONTAINED_BY
- Set when other is a descendant of node.
node .
contains(other)
- Returns true if other is an inclusive descendant of node; otherwise false.
These are the constants compareDocumentPosition()
returns as mask:
DOCUMENT_POSITION_DISCONNECTED
(1);DOCUMENT_POSITION_PRECEDING
(2);DOCUMENT_POSITION_FOLLOWING
(4);DOCUMENT_POSITION_CONTAINS
(8);DOCUMENT_POSITION_CONTAINED_BY
(16, 10 in hexadecimal);DOCUMENT_POSITION_IMPLEMENTATION_SPECIFIC
(32, 20 in hexadecimal).
The compareDocumentPosition(other)
method
steps are:
-
If this is other, then return zero.
-
Let node1 be other and node2 be this.
-
Let attr1 and attr2 be null.
-
If node1 is an attribute, then set attr1 to node1 and node1 to attr1’s element.
-
If node2 is an attribute, then:
-
Set attr2 to node2 and node2 to attr2’s element.
-
If attr1 and node1 are non-null, and node2 is node1, then:
-
For each attr in node2’s attribute list:
-
If attr equals attr1, then return the result of adding
DOCUMENT_POSITION_IMPLEMENTATION_SPECIFIC
andDOCUMENT_POSITION_PRECEDING
. -
If attr equals attr2, then return the result of adding
DOCUMENT_POSITION_IMPLEMENTATION_SPECIFIC
andDOCUMENT_POSITION_FOLLOWING
.
-
-
-
-
If node1 or node2 is null, or node1’s root is not node2’s root, then return the result of adding
DOCUMENT_POSITION_DISCONNECTED
,DOCUMENT_POSITION_IMPLEMENTATION_SPECIFIC
, and eitherDOCUMENT_POSITION_PRECEDING
orDOCUMENT_POSITION_FOLLOWING
, with the constraint that this is to be consistent, together.Whether to return
DOCUMENT_POSITION_PRECEDING
orDOCUMENT_POSITION_FOLLOWING
is typically implemented via pointer comparison. In JavaScript implementations a cachedMath
value can be used.. random() -
If node1 is an ancestor of node2 and attr1 is null, or node1 is node2 and attr2 is non-null, then return the result of adding
DOCUMENT_POSITION_CONTAINS
toDOCUMENT_POSITION_PRECEDING
. -
If node1 is a descendant of node2 and attr2 is null, or node1 is node2 and attr1 is non-null, then return the result of adding
DOCUMENT_POSITION_CONTAINED_BY
toDOCUMENT_POSITION_FOLLOWING
. -
If node1 is preceding node2, then return
DOCUMENT_POSITION_PRECEDING
.Due to the way attributes are handled in this algorithm this results in a node’s attributes counting as preceding that node’s children, despite attributes not participating in the same tree.
-
Return
DOCUMENT_POSITION_FOLLOWING
.
The contains(other)
method steps are to return
true if other is an inclusive descendant of this; otherwise false
(including when other is null).
To locate a namespace prefix for an element using namespace, run these steps:
-
If element’s namespace is namespace and its namespace prefix is non-null, then return its namespace prefix.
-
If element has an attribute whose namespace prefix is "
xmlns
" and value is namespace, then return element’s first such attribute’s local name. -
If element’s parent element is not null, then return the result of running locate a namespace prefix on that element using namespace.
-
Return null.
To locate a namespace for a node using prefix, switch on the interface node implements:
Element
-
-
If prefix is "
xml
", then return the XML namespace. -
If prefix is "
xmlns
", then return the XMLNS namespace. -
If its namespace is non-null and its namespace prefix is prefix, then return namespace.
-
If it has an attribute whose namespace is the XMLNS namespace, namespace prefix is "
xmlns
", and local name is prefix, or if prefix is null and it has an attribute whose namespace is the XMLNS namespace, namespace prefix is null, and local name is "xmlns
", then return its value if it is not the empty string, and null otherwise. -
If its parent element is null, then return null.
-
Return the result of running locate a namespace on its parent element using prefix.
-
Document
-
-
If its document element is null, then return null.
-
Return the result of running locate a namespace on its document element using prefix.
-
DocumentType
DocumentFragment
-
Return null.
Attr
-
-
If its element is null, then return null.
-
Return the result of running locate a namespace on its element using prefix.
-
- Otherwise
-
-
If its parent element is null, then return null.
-
Return the result of running locate a namespace on its parent element using prefix.
-
The lookupPrefix(namespace)
method steps are:
-
If namespace is null or the empty string, then return null.
-
Switch on the interface this implements:
Element
-
Return the result of locating a namespace prefix for this using namespace.
Document
-
-
If this’s document element is null, then return null.
-
Return the result of locating a namespace prefix for this’s document element using namespace.
-
DocumentType
DocumentFragment
-
Return null.
Attr
-
-
Return the result of locating a namespace prefix for this’s element using namespace.
- Otherwise
-
-
If this’s parent element is null, then return null.
-
Return the result of locating a namespace prefix for this’s parent element using namespace.
-
The lookupNamespaceURI(prefix)
method steps
are:
-
If prefix is the empty string, then set it to null.
-
Return the result of running locate a namespace for this using prefix.
The isDefaultNamespace(namespace)
method steps
are:
-
If namespace is the empty string, then set it to null.
-
Let defaultNamespace be the result of running locate a namespace for this using null.
-
Return true if defaultNamespace is the same as namespace; otherwise false.
The insertBefore(node, child)
method steps are to return the result of pre-inserting node into this before child.
The appendChild(node)
method steps are to
return the result of appending node to this.
The replaceChild(node, child)
method steps are to return the result of replacing child with node within this.
The removeChild(child)
method steps are to
return the result of pre-removing child from this.
The list of elements with qualified name qualifiedName for a node root is the HTMLCollection
returned by the following
algorithm:
-
If qualifiedName is U+002A (*), then return an
HTMLCollection
rooted at root, whose filter matches only descendant elements. -
Otherwise, if root’s node document is an HTML document, return an
HTMLCollection
rooted at root, whose filter matches the following descendant elements:-
Whose namespace is the HTML namespace and whose qualified name is qualifiedName, in ASCII lowercase.
-
Whose namespace is not the HTML namespace and whose qualified name is qualifiedName.
-
-
Otherwise, return an
HTMLCollection
rooted at root, whose filter matches descendant elements whose qualified name is qualifiedName.
When invoked with the same argument, and as long as root’s node document’s type has not changed, the same HTMLCollection
object may be returned as returned by an earlier call.
The list of elements with namespace namespace and local name localName for a node root is the HTMLCollection
returned by the following
algorithm:
-
If namespace is the empty string, then set it to null.
-
If both namespace and localName are U+002A (*), then return an
HTMLCollection
rooted at root, whose filter matches descendant elements. -
If namespace is U+002A (*), then return an
HTMLCollection
rooted at root, whose filter matches descendant elements whose local name is localName. -
If localName is U+002A (*), then return an
HTMLCollection
rooted at root, whose filter matches descendant elements whose namespace is namespace. -
Return an
HTMLCollection
rooted at root, whose filter matches descendant elements whose namespace is namespace and local name is localName.
When invoked with the same arguments, the same HTMLCollection
object may be returned as
returned by an earlier call.
The list of elements with class names classNames for a node root is the HTMLCollection
returned by the following
algorithm:
- Let classes be the result of running the ordered set parser on classNames.
- If classes is the empty set, return an empty
HTMLCollection
. -
Return an
HTMLCollection
rooted at root, whose filter matches descendant elements that have all their classes in classes.The comparisons for the classes must be done in an ASCII case-insensitive manner if root’s node document’s mode is "
quirks
"; otherwise in an identical to manner.
When invoked with the same argument, the same HTMLCollection
object may be returned as
returned by an earlier call.
4.5. Interface Document
[Exposed =Window ]interface :
Document Node {constructor (); [SameObject ]readonly attribute DOMImplementation implementation ;readonly attribute USVString URL ;readonly attribute USVString documentURI ;readonly attribute DOMString compatMode ;readonly attribute DOMString characterSet ;readonly attribute DOMString charset ; // legacy alias of .characterSetreadonly attribute DOMString inputEncoding ; // legacy alias of .characterSetreadonly attribute DOMString contentType ;readonly attribute DocumentType ?doctype ;readonly attribute Element ?documentElement ;HTMLCollection getElementsByTagName (DOMString );
qualifiedName HTMLCollection getElementsByTagNameNS (DOMString ?,
namespace DOMString );
localName HTMLCollection getElementsByClassName (DOMString ); [
classNames CEReactions ,NewObject ]Element createElement (DOMString ,
localName optional (DOMString or ElementCreationOptions )= {}); [
options CEReactions ,NewObject ]Element createElementNS (DOMString ?,
namespace DOMString ,
qualifiedName optional (DOMString or ElementCreationOptions )= {}); [
options NewObject ]DocumentFragment createDocumentFragment (); [NewObject ]Text createTextNode (DOMString ); [
data NewObject ]CDATASection createCDATASection (DOMString ); [
data NewObject ]Comment createComment (DOMString ); [
data NewObject ]ProcessingInstruction createProcessingInstruction (DOMString ,
target DOMString ); [
data CEReactions ,NewObject ]Node importNode (Node ,
node optional boolean =
deep false ); [CEReactions ]Node adoptNode (Node ); [
node NewObject ]Attr createAttribute (DOMString ); [
localName NewObject ]Attr createAttributeNS (DOMString ?,
namespace DOMString ); [
qualifiedName NewObject ]Event createEvent (DOMString ); // legacy [
interface NewObject ]Range createRange (); // NodeFilter.SHOW_ALL = 0xFFFFFFFF [NewObject ]NodeIterator createNodeIterator (Node ,
root optional unsigned long = 0xFFFFFFFF,
whatToShow optional NodeFilter ?=
filter null ); [NewObject ]TreeWalker createTreeWalker (Node ,
root optional unsigned long = 0xFFFFFFFF,
whatToShow optional NodeFilter ?=
filter null ); }; [Exposed =Window ]interface :
XMLDocument Document {};dictionary {
ElementCreationOptions DOMString ; };
is
Document
nodes are simply
known as documents.
A document’s node document is itself.
Each document has an associated encoding (an encoding), content type (a string), URL (a URL), origin (an origin), type ("xml
" or "html
"), mode ("no-quirks
", "quirks
", or "limited-quirks
"), and allow declarative shadow roots (a boolean). [ENCODING] [URL] [HTML]
Unless stated otherwise, a document’s encoding is the utf-8 encoding, content type is
"application/xml
", URL is "about:blank
", origin is an opaque origin, type is "xml
", mode is
"no-quirks
", and its allow declarative shadow roots is false.
A document is said to be an XML document if its type is "xml
"; otherwise an HTML document. Whether a document is an HTML document or an XML document affects the behavior of certain APIs.
A document is said to be in no-quirks mode if its mode is "no-quirks
", quirks mode if its mode is "quirks
", and limited-quirks mode if its mode is "limited-quirks
".
The mode is only ever changed from the default for documents created
by the HTML parser based on the presence, absence, or value of the DOCTYPE string, and by a
new browsing context (initial "about:blank
"). [HTML]
No-quirks mode was originally known as "standards mode" and limited-quirks mode was once known as "almost standards mode". They have been renamed because their details are now defined by standards. (And because Ian Hickson vetoed their original names on the basis that they are nonsensical.)
A document’s get the parent algorithm, given an event, returns
null if event’s type
attribute value is "load
" or document does not have a browsing context; otherwise the document’s relevant global object.
document = new
Document()
- Returns a new document.
document .
implementation
- Returns document’s
DOMImplementation
object. document .
URL
document .
documentURI
- Returns document’s URL.
document .
compatMode
- Returns the string "
BackCompat
" if document’s mode is "quirks
"; otherwise "CSS1Compat
". document .
characterSet
- Returns document’s encoding.
document .
contentType
- Returns document’s content type.
The new Document()
constructor
steps are to set this’s origin to the origin of current global object’s associated Document
. [HTML]
Unlike createDocument()
, this constructor does not
return an XMLDocument
object, but a document (Document
object).
The implementation
getter steps are to return the DOMImplementation
object that is associated with this.
The URL
and documentURI
getter steps are to return this’s URL, serialized.
The compatMode
getter steps are to return
"BackCompat
" if this’s mode is "quirks
";
otherwise "CSS1Compat
".
The characterSet
, charset
, and inputEncoding
getter steps are to return this’s encoding’s name.
The contentType
getter steps are to return this’s content type.
- document .
doctype
- Returns the doctype or null if there is none.
- document .
documentElement
- Returns the document element.
- collection = document .
getElementsByTagName(qualifiedName)
-
If qualifiedName is "
*
" returns anHTMLCollection
of all descendant elements.Otherwise, returns an
HTMLCollection
of all descendant elements whose qualified name is qualifiedName. (Matches case-insensitively against elements in the HTML namespace within an HTML document.) - collection = document .
getElementsByTagNameNS(namespace, localName)
-
If namespace and localName are "
*
", returns anHTMLCollection
of all descendant elements.If only namespace is "
*
", returns anHTMLCollection
of all descendant elements whose local name is localName.If only localName is "
*
", returns anHTMLCollection
of all descendant elements whose namespace is namespace.Otherwise, returns an
HTMLCollection
of all descendant elements whose namespace is namespace and local name is localName. - collection = document .
getElementsByClassName(classNames)
- collection = element .
getElementsByClassName(classNames)
- collection = element .
-
Returns an
HTMLCollection
of the elements in the object on which the method was invoked (a document or an element) that have all the classes given by classNames. The classNames argument is interpreted as a space-separated list of classes.
The doctype
getter steps are to return the child of this that is a doctype; otherwise null.
The documentElement
getter steps are to return this’s document element.
The getElementsByTagName(qualifiedName)
method steps are to return the list of elements with qualified name qualifiedName for this.
Thus, in an HTML document, document
will match <FOO>
elements that are not in the HTML namespace, and <foo>
elements that are in
the HTML namespace, but not <FOO>
elements
that are in the HTML namespace.
The getElementsByTagNameNS(namespace, localName)
method steps are to return the list of elements with namespace namespace and local
name localName for this.
The getElementsByClassName(classNames)
method steps are to return the list of elements with class names classNames for this.
< div id = "example" >
< p id = "p1" class = "aaa bbb" />
< p id = "p2" class = "aaa ccc" />
< p id = "p3" class = "bbb ccc" />
</ div >
A call to document
would return an HTMLCollection
with the two paragraphs p1
and p2
in it.
A call to getElementsByClassName
would only return one node, however, namely p3
. A call to document
would return the same thing.
A call to getElementsByClassName
would return no nodes; none of the elements above are in the aaa,bbb
class.
element = document . createElement(localName [, options])
-
Returns an element with localName as local name (if document is an HTML document, localName gets lowercased). The element’s namespace is the HTML namespace when document is an HTML document or document’s content type is "
application/xhtml+xml
"; otherwise null.If localName does not match the
Name
production an "InvalidCharacterError
"DOMException
will be thrown.When supplied, options’s
is
can be used to create a customized built-in element. element = document . createElementNS(namespace, qualifiedName [, options])
-
Returns an element with namespace namespace. Its namespace prefix will be everything before U+003A (:) in qualifiedName or null. Its local name will be everything after U+003A (:) in qualifiedName or qualifiedName.
If qualifiedName does not match the
QName
production an "InvalidCharacterError
"DOMException
will be thrown.If one of the following conditions is true a "
NamespaceError
"DOMException
will be thrown:- Namespace prefix is not null and namespace is the empty string.
- Namespace prefix is "
xml
" and namespace is not the XML namespace. - qualifiedName or namespace prefix is "
xmlns
" and namespace is not the XMLNS namespace. - namespace is the XMLNS namespace and
neither qualifiedName nor namespace prefix is "
xmlns
".
When supplied, options’s
is
can be used to create a customized built-in element. documentFragment = document .
createDocumentFragment()
- Returns a
DocumentFragment
node. text = document .
createTextNode(data)
- Returns a
Text
node whose data is data. text = document .
createCDATASection(data)
- Returns a
CDATASection
node whose data is data. comment = document .
createComment(data)
- Returns a
Comment
node whose data is data. processingInstruction = document .
createProcessingInstruction(target, data)
- Returns a
ProcessingInstruction
node whose target is target and data is data. If target does not match theName
production an "InvalidCharacterError
"DOMException
will be thrown. If data contains "?>
" an "InvalidCharacterError
"DOMException
will be thrown.
The element interface for any name and namespace is Element
, unless stated otherwise.
The HTML Standard will, e.g., define that for html
and the HTML namespace, the HTMLHtmlElement
interface is used. [HTML]
The createElement(localName, options)
method steps are:
-
If localName does not match the
Name
production, then throw an "InvalidCharacterError
"DOMException
. -
If this is an HTML document, then set localName to localName in ASCII lowercase.
-
Let is be null.
-
If options is a dictionary and options["
is
"] exists, then set is to it. -
Let namespace be the HTML namespace, if this is an HTML document or this’s content type is "
application/xhtml+xml
"; otherwise null. -
Return the result of creating an element given this, localName, namespace, null, is, and with the synchronous custom elements flag set.
The internal createElementNS
steps, given document, namespace, qualifiedName, and options, are as follows:
-
Let namespace, prefix, and localName be the result of passing namespace and qualifiedName to validate and extract.
-
Let is be null.
-
If options is a dictionary and options["
is
"] exists, then set is to it. -
Return the result of creating an element given document, localName, namespace, prefix, is, and with the synchronous custom elements flag set.
The createElementNS(namespace, qualifiedName, options)
method steps are to return the result of running the internal createElementNS
steps, given this, namespace, qualifiedName, and options.
createElement()
and createElementNS()
's options parameter is allowed to be a string for web compatibility.
The createDocumentFragment()
method steps are to
return a new DocumentFragment
node whose node document is this.
The createTextNode(data)
method steps are
to return a new Text
node whose data is data and node document is this.
No check is performed that data consists of
characters that match the Char
production.
The createCDATASection(data)
method steps
are:
-
If this is an HTML document, then throw a "
NotSupportedError
"DOMException
. -
If data contains the string "
]]>
", then throw an "InvalidCharacterError
"DOMException
. -
Return a new
CDATASection
node with its data set to data and node document set to this.
The createComment(data)
method steps are
to return a new Comment
node whose data is data and node document is this.
No check is performed that data consists of
characters that match the Char
production
or that it contains two adjacent hyphens or ends with a hyphen.
The createProcessingInstruction(target, data)
method steps are:
- If target does not match the
Name
production, then throw an "InvalidCharacterError
"DOMException
. - If data contains the string
"
?>
", then throw an "InvalidCharacterError
"DOMException
. - Return a new
ProcessingInstruction
node, with target set to target, data set to data, and node document set to this.
No check is performed that target contains
"xml
" or ":
", or that data contains characters that match the Char
production.
- clone = document . importNode(node [, deep = false])
-
Returns a copy of node. If deep is true, the copy also includes the node’s descendants.
If node is a document or a shadow root, throws a "
NotSupportedError
"DOMException
. - node = document .
adoptNode(node)
-
Moves node from another document and returns it.
If node is a document, throws a "
NotSupportedError
"DOMException
or, if node is a shadow root, throws a "HierarchyRequestError
"DOMException
.
The importNode(node, deep)
method steps are:
-
If node is a document or shadow root, then throw a "
NotSupportedError
"DOMException
. -
Return a clone of node, with this and the clone children flag set if deep is true.
Specifications may define adopting steps for all or some nodes. The algorithm is passed node and oldDocument, as indicated in the adopt algorithm.
To adopt a node into a document, run these steps:
-
Let oldDocument be node’s node document.
-
If document is not oldDocument, then:
-
For each inclusiveDescendant in node’s shadow-including inclusive descendants:
-
Set inclusiveDescendant’s node document to document.
-
If inclusiveDescendant is an element, then set the node document of each attribute in inclusiveDescendant’s attribute list to document.
-
-
For each inclusiveDescendant in node’s shadow-including inclusive descendants that is custom, enqueue a custom element callback reaction with inclusiveDescendant, callback name "
adoptedCallback
", and an argument list containing oldDocument and document. -
For each inclusiveDescendant in node’s shadow-including inclusive descendants, in shadow-including tree order, run the adopting steps with inclusiveDescendant and oldDocument.
-
The adoptNode(node)
method steps are:
-
If node is a document, then throw a "
NotSupportedError
"DOMException
. -
If node is a shadow root, then throw a "
HierarchyRequestError
"DOMException
. -
If node is a
DocumentFragment
node whose host is non-null, then return. -
Return node.
The createAttribute(localName)
method
steps are:
-
If localName does not match the
Name
production in XML, then throw an "InvalidCharacterError
"DOMException
. - If this is an HTML document, then set localName to localName in ASCII lowercase.
- Return a new attribute whose local name is localName and node document is this.
The createAttributeNS(namespace, qualifiedName)
method steps are:
-
Let namespace, prefix, and localName be the result of passing namespace and qualifiedName to validate and extract.
-
Return a new attribute whose namespace is namespace, namespace prefix is prefix, local name is localName, and node document is this.
The createEvent(interface)
method steps
are:
-
Let constructor be null.
-
If interface is an ASCII case-insensitive match for any of the strings in the first column in the following table, then set constructor to the interface in the second column on the same row as the matching string:
String Interface Notes " beforeunloadevent
"BeforeUnloadEvent
[HTML] " compositionevent
"CompositionEvent
[UIEVENTS] " customevent
"CustomEvent
" devicemotionevent
"DeviceMotionEvent
[DEVICE-ORIENTATION] " deviceorientationevent
"DeviceOrientationEvent
" dragevent
"DragEvent
[HTML] " event
"Event
" events
"" focusevent
"FocusEvent
[UIEVENTS] " hashchangeevent
"HashChangeEvent
[HTML] " htmlevents
"Event
" keyboardevent
"KeyboardEvent
[UIEVENTS] " messageevent
"MessageEvent
[HTML] " mouseevent
"MouseEvent
[UIEVENTS] " mouseevents
"" storageevent
"StorageEvent
[HTML] " svgevents
"Event
" textevent
"TextEvent
[UIEVENTS] " touchevent
"TouchEvent
[TOUCH-EVENTS] " uievent
"UIEvent
[UIEVENTS] " uievents
" -
If constructor is null, then throw a "
NotSupportedError
"DOMException
. -
If the interface indicated by constructor is not exposed on the relevant global object of this, then throw a "
NotSupportedError
"DOMException
.Typically user agents disable support for touch events in some configurations, in which case this clause would be triggered for the interface
TouchEvent
. -
Let event be the result of creating an event given constructor.
-
Initialize event’s
type
attribute to the empty string. -
Initialize event’s
timeStamp
attribute to the result of calling current high resolution time with this’s relevant global object. -
Initialize event’s
isTrusted
attribute to false. -
Unset event’s initialized flag.
-
Return event.
Event constructors ought to be used instead.
The createRange()
method steps are to return a new live range with (this, 0) as its start an end.
The Range()
constructor can be used instead.
The createNodeIterator(root, whatToShow, filter)
method steps are:
-
Let iterator be a new
NodeIterator
object. -
Set iterator’s pointer before reference to true.
-
Set iterator’s whatToShow to whatToShow.
-
Set iterator’s filter to filter.
-
Return iterator.
The createTreeWalker(root, whatToShow, filter)
method steps are:
-
Let walker be a new
TreeWalker
object. -
Set walker’s whatToShow to whatToShow.
-
Set walker’s filter to filter.
- Return walker.
4.5.1. Interface DOMImplementation
User agents must create a DOMImplementation
object whenever
a document is created and associate it
with that document.
[Exposed =Window ]interface { [
DOMImplementation NewObject ]DocumentType createDocumentType (DOMString ,
qualifiedName DOMString ,
publicId DOMString ); [
systemId NewObject ]XMLDocument createDocument (DOMString ?, [
namespace LegacyNullToEmptyString ]DOMString ,
qualifiedName optional DocumentType ?=
doctype null ); [NewObject ]Document createHTMLDocument (optional DOMString );
title boolean hasFeature (); // useless; always returns true };
doctype = document .
implementation
.createDocumentType(qualifiedName, publicId, systemId)
- Returns a doctype, with the given qualifiedName, publicId, and systemId. If qualifiedName does not
match the
Name
production, an "InvalidCharacterError
"DOMException
is thrown, and if it does not match theQName
production, a "NamespaceError
"DOMException
is thrown. doc = document .
implementation
. createDocument(namespace, qualifiedName [, doctype = null])-
Returns an
XMLDocument
, with a document element whose local name is qualifiedName and whose namespace is namespace (unless qualifiedName is the empty string), and with doctype, if it is given, as its doctype.This method throws the same exceptions as the
createElementNS()
method, when invoked with namespace and qualifiedName. doc = document .
implementation
. createHTMLDocument([title])- Returns a document, with a basic tree already constructed including a
title
element, unless the title argument is omitted.
The createDocumentType(qualifiedName, publicId, systemId)
method steps are:
-
Validate qualifiedName.
-
Return a new doctype, with qualifiedName as its name, publicId as its public ID, and systemId as its system ID, and with its node document set to the associated document of this.
No check is performed that publicId code points match the PubidChar
production or that systemId does not contain both a
'"
' and a "'
".
The createDocument(namespace, qualifiedName, doctype)
method steps are:
-
Let document be a new
XMLDocument
. -
Let element be null.
-
If qualifiedName is not the empty string, then set element to the result of running the internal
createElementNS
steps, given document, namespace, qualifiedName, and an empty dictionary. -
If doctype is non-null, append doctype to document.
-
If element is non-null, append element to document.
-
document’s content type is determined by namespace:
- HTML namespace
application/xhtml+xml
- SVG namespace
image/svg+xml
- Any other namespace
application/xml
-
Return document.
The createHTMLDocument(title)
method steps are:
-
Let doc be a new document that is an HTML document.
-
Set doc’s content type to "
text/html
". -
Append a new doctype, with "
html
" as its name and with its node document set to doc, to doc. -
Append the result of creating an element given doc,
html
, and the HTML namespace, to doc. -
Append the result of creating an element given doc,
head
, and the HTML namespace, to thehtml
element created earlier. -
If title is given:
-
Append the result of creating an element given doc,
title
, and the HTML namespace, to thehead
element created earlier. -
Append a new
Text
node, with its data set to title (which could be the empty string) and its node document set to doc, to thetitle
element created earlier.
-
-
Append the result of creating an element given doc,
body
, and the HTML namespace, to thehtml
element created earlier. -
Return doc.
The hasFeature()
method steps are to
return true.
hasFeature()
originally would report whether the user agent
claimed to support a given DOM feature, but experience proved it was not nearly as
reliable or granular as simply checking whether the desired objects, attributes, or
methods existed. As such, it is no longer to be used, but continues to exist (and simply
returns true) so that old pages don’t stop working.
4.6. Interface DocumentType
[Exposed =Window ]interface :
DocumentType Node {readonly attribute DOMString name ;readonly attribute DOMString publicId ;readonly attribute DOMString systemId ; };
DocumentType
nodes are simply known as doctypes.
Doctypes have an associated name, public ID, and system ID.
When a doctype is created, its name is always given. Unless explicitly given when a doctype is created, its public ID and system ID are the empty string.
The name
getter steps are to return this’s name.
The publicId
getter steps are to return this’s public ID.
The systemId
getter steps are to return this’s system ID.
4.7. Interface DocumentFragment
[Exposed =Window ]interface :
DocumentFragment Node {constructor (); };
A DocumentFragment
node has an associated host (null or an element in a different node tree). It is null unless otherwise stated.
An object A is a host-including inclusive ancestor of an object B, if either A is an inclusive ancestor of B, or if B’s root has a non-null host and A is a host-including inclusive ancestor of B’s root’s host.
The DocumentFragment
node’s host concept is useful for HTML’s template
element and for shadow roots, and impacts the pre-insert and replace algorithms.
tree = new
DocumentFragment()
- Returns a new
DocumentFragment
node.
The new DocumentFragment()
constructor steps are to set this’s node document to current global object’s associated Document
.
4.8. Interface ShadowRoot
[Exposed =Window ]interface :
ShadowRoot DocumentFragment {readonly attribute ShadowRootMode mode ;readonly attribute boolean delegatesFocus ;readonly attribute SlotAssignmentMode slotAssignment ;readonly attribute boolean clonable ;readonly attribute boolean serializable ;readonly attribute Element host ;attribute EventHandler onslotchange ; };enum {
ShadowRootMode ,
"open" };
"closed" enum {
SlotAssignmentMode ,
"manual" };
"named"
ShadowRoot
nodes are simply known as shadow roots.
Shadow roots have an associated mode ("open
"
or "closed
").
Shadow roots have an associated delegates focus. It is initially set to false.
Shadow roots have an associated available to element internals. It is initially set to false.
Shadow roots have an associated declarative (a boolean). It is initially set to false.
Shadow roots’s associated host is never null.
Shadow roots have an associated slot assignment ("manual
" or "named
").
Shadow roots have an associated clonable (a boolean). It is initially set to false.
Shadow roots have an associated serializable (a boolean). It is initially set to false.
A shadow root’s get the parent algorithm, given an event, returns null if event’s composed flag is unset and shadow root is the root of event’s path’s first struct’s invocation target; otherwise shadow root’s host.
The mode
getter steps are to return this’s mode.
The delegatesFocus
getter steps are to return this’s delegates focus.
The slotAssignment
getter steps are to return this’s slot assignment.
The clonable
getter steps are to return this’s clonable.
The serializable
getter steps are to return this’s serializable.
The host
getter steps are to return this’s host.
The onslotchange
attribute is an event handler IDL attribute for the onslotchange
event handler, whose event handler event type is slotchange
.
In shadow-including tree order is shadow-including preorder, depth-first traversal of a node tree. Shadow-including preorder, depth-first traversal of a node tree tree is preorder, depth-first traversal of tree, with for each shadow host encountered in tree, shadow-including preorder, depth-first traversal of that element’s shadow root’s node tree just after it is encountered.
The shadow-including root of an object is its root’s host’s shadow-including root, if the object’s root is a shadow root; otherwise its root.
An object A is a shadow-including descendant of an object B, if A is a descendant of B, or A’s root is a shadow root and A’s root’s host is a shadow-including inclusive descendant of B.
A shadow-including inclusive descendant is an object or one of its shadow-including descendants.
An object A is a shadow-including ancestor of an object B, if and only if B is a shadow-including descendant of A.
A shadow-including inclusive ancestor is an object or one of its shadow-including ancestors.
A node A is closed-shadow-hidden from a node B if all of the following conditions are true:
-
A’s root is a shadow root.
-
A’s root is not a shadow-including inclusive ancestor of B.
-
A’s root is a shadow root whose mode is "
closed
" or A’s root’s host is from B.
To retarget an object A against an object B, repeat these steps until they return an object:
-
If one of the following is true
- A is not a node
- A’s root is not a shadow root
- B is a node and A’s root is a shadow-including inclusive ancestor of B
then return A.
The retargeting algorithm is used by event dispatch as well as other specifications, such as Fullscreen. [FULLSCREEN]
4.9. Interface Element
[Exposed =Window ]interface :
Element Node {readonly attribute DOMString ?namespaceURI ;readonly attribute DOMString ?prefix ;readonly attribute DOMString localName ;readonly attribute DOMString tagName ; [CEReactions ]attribute DOMString id ; [CEReactions ]attribute DOMString className ; [SameObject ,PutForwards =value ]readonly attribute DOMTokenList classList ; [CEReactions ,Unscopable ]attribute DOMString slot ;boolean hasAttributes (); [SameObject ]readonly attribute NamedNodeMap attributes ;sequence <DOMString >getAttributeNames ();DOMString ?getAttribute (DOMString );
qualifiedName DOMString ?getAttributeNS (DOMString ?,
namespace DOMString ); [
localName CEReactions ]undefined setAttribute (DOMString ,
qualifiedName DOMString ); [
value CEReactions ]undefined setAttributeNS (DOMString ?,
namespace DOMString ,
qualifiedName DOMString ); [
value CEReactions ]undefined removeAttribute (DOMString ); [
qualifiedName CEReactions ]undefined removeAttributeNS (DOMString ?,
namespace DOMString ); [
localName CEReactions ]boolean toggleAttribute (DOMString ,
qualifiedName optional boolean );
force boolean hasAttribute (DOMString );
qualifiedName boolean hasAttributeNS (DOMString ?,
namespace DOMString );
localName Attr ?getAttributeNode (DOMString );
qualifiedName Attr ?getAttributeNodeNS (DOMString ?,
namespace DOMString ); [
localName CEReactions ]Attr ?setAttributeNode (Attr ); [
attr CEReactions ]Attr ?setAttributeNodeNS (Attr ); [
attr CEReactions ]Attr removeAttributeNode (Attr );
attr ShadowRoot attachShadow (ShadowRootInit );
init readonly attribute ShadowRoot ?shadowRoot ;Element ?closest (DOMString );
selectors boolean matches (DOMString );
selectors boolean webkitMatchesSelector (DOMString ); // legacy alias of .matches
selectors HTMLCollection getElementsByTagName (DOMString );
qualifiedName HTMLCollection getElementsByTagNameNS (DOMString ?,
namespace DOMString );
localName HTMLCollection getElementsByClassName (DOMString ); [
classNames CEReactions ]Element ?insertAdjacentElement (DOMString ,
where Element ); // legacy
element undefined insertAdjacentText (DOMString ,
where DOMString ); // legacy };
data dictionary {
ShadowRootInit required ShadowRootMode ;
mode boolean =
delegatesFocus false ;SlotAssignmentMode = "named";
slotAssignment boolean =
clonable false ;boolean =
serializable false ; };
Element
nodes are simply known as elements.
Elements have an associated namespace, namespace prefix, local name, custom element state, custom element definition, is
value. When an element is created, all of these values are
initialized.
An element’s custom element state is one of
"undefined
", "failed
", "uncustomized
",
"precustomized
", or "custom
". An element whose custom element state is "uncustomized
" or "custom
" is
said to be defined. An element whose custom element state is "custom
" is said to be custom.
Whether or not an element is defined is used to determine the
behavior of the :defined pseudo-class. Whether or not an element is custom is
used to determine the behavior of the mutation algorithms. The
"failed
" and "precustomized
" states are used to ensure that if a custom element constructor fails to execute correctly the first time, it is not executed
again by an upgrade.
The following code illustrates elements in each of these four states:
<!DOCTYPE html>
< script >
window. customElements. define( "sw-rey" , class extends HTMLElement {})
window. customElements. define( "sw-finn" , class extends HTMLElement {}, { extends : "p" })
window. customElements. define( "sw-kylo" , class extends HTMLElement {
constructor () {
// super() intentionally omitted for this example
}
})
</ script >
<!-- "undefined" (not defined, not custom) -->
< sw-han ></ sw-han >
< p is = "sw-luke" ></ p >
< p is = "asdf" ></ p >
<!-- "failed" (not defined, not custom) -->
< sw-kylo ></ sw-kylo >
<!-- "uncustomized" (defined, not custom) -->
< p ></ p >
< asdf ></ asdf >
<!-- "custom" (defined, custom) -->
< sw-rey ></ sw-rey >
< p is = "sw-finn" ></ p >
Elements also have an associated shadow root (null or a shadow root). It is null unless otherwise stated. An element is a shadow host if its shadow root is non-null.
An element’s qualified name is its local name if its namespace prefix is null; otherwise its namespace prefix, followed by ":
", followed by its local name.
An element’s HTML-uppercased qualified name is the return value of these steps:
-
Let qualifiedName be this’s qualified name.
-
If this is in the HTML namespace and its node document is an HTML document, then set qualifiedName to qualifiedName in ASCII uppercase.
- Return qualifiedName.
User agents could optimize qualified name and HTML-uppercased qualified name by storing them in internal slots.
To create an element, given a document, localName, namespace, and optional prefix, is, and synchronous custom elements flag, run these steps:
-
If prefix was not given, let prefix be null.
-
If is was not given, let is be null.
-
Let result be null.
-
Let definition be the result of looking up a custom element definition given document, namespace, localName, and is.
-
If definition is non-null, and definition’s name is not equal to its local name (i.e., definition represents a customized built-in element), then:
-
Let interface be the element interface for localName and the HTML namespace.
-
Set result to a new element that implements interface, with no attributes, namespace set to the HTML namespace, namespace prefix set to prefix, local name set to localName, custom element state set to "
undefined
", custom element definition set to null,is
value set to is, and node document set to document. -
If the synchronous custom elements flag is set, then run this step while catching any exceptions:
-
Upgrade result using definition.
If this step threw an exception exception:
-
Report exception for definition’s constructor’s corresponding JavaScript object’s associated realm’s global object.
-
Set result’s custom element state to "
failed
".
-
-
Otherwise, enqueue a custom element upgrade reaction given result and definition.
-
-
Otherwise, if definition is non-null:
-
If the synchronous custom elements flag is set, then run these steps while catching any exceptions:
-
Let C be definition’s constructor.
-
Set result to the result of constructing C, with no arguments.
-
Assert: result’s custom element state and custom element definition are initialized.
-
Assert: result’s namespace is the HTML namespace.
IDL enforces that result is an
HTMLElement
object, which all use the HTML namespace. -
If result’s attribute list is not empty, then throw a "
NotSupportedError
"DOMException
. -
If result has children, then throw a "
NotSupportedError
"DOMException
. -
If result’s parent is not null, then throw a "
NotSupportedError
"DOMException
. -
If result’s node document is not document, then throw a "
NotSupportedError
"DOMException
. -
If result’s local name is not equal to localName, then throw a "
NotSupportedError
"DOMException
. -
Set result’s namespace prefix to prefix.
-
Set result’s
is
value to null.
If any of these steps threw an exception exception:
-
Report exception for definition’s constructor’s corresponding JavaScript object’s associated realm’s global object.
-
Set result to a new element that implements the
HTMLUnknownElement
interface, with no attributes, namespace set to the HTML namespace, namespace prefix set to prefix, local name set to localName, custom element state set to "failed
", custom element definition set to null,is
value set to null, and node document set to document.
-
-
Otherwise:
-
Set result to a new element that implements the
HTMLElement
interface, with no attributes, namespace set to the HTML namespace, namespace prefix set to prefix, local name set to localName, custom element state set to "undefined
", custom element definition set to null,is
value set to null, and node document set to document. -
Enqueue a custom element upgrade reaction given result and definition.
-
-
-
Otherwise:
-
Let interface be the element interface for localName and namespace.
-
Set result to a new element that implements interface, with no attributes, namespace set to namespace, namespace prefix set to prefix, local name set to localName, custom element state set to "
uncustomized
", custom element definition set to null,is
value set to is, and node document set to document. -
If namespace is the HTML namespace, and either localName is a valid custom element name or is is non-null, then set result’s custom element state to "
undefined
".
-
-
Return result.
Elements also have an attribute list, which is a list exposed through a NamedNodeMap
. Unless explicitly given when an element is created, its attribute list is empty.
An element has an attribute A if its attribute list contains A.
This and other specifications may define attribute change steps for elements. The algorithm is passed element, localName, oldValue, value, and namespace.
To handle attribute changes for an attribute attribute with element, oldValue, and newValue, run these steps:
-
Queue a mutation record of "
attributes
" for element with attribute’s local name, attribute’s namespace, oldValue, « », « », null, and null. -
If element is custom, then enqueue a custom element callback reaction with element, callback name "
attributeChangedCallback
", and an argument list containing attribute’s local name, oldValue, newValue, and attribute’s namespace. -
Run the attribute change steps with element, attribute’s local name, oldValue, newValue, and attribute’s namespace.
To change an attribute attribute to value, run these steps:
-
Let oldValue be attribute’s value.
-
Set attribute’s value to value.
-
Handle attribute changes for attribute with attribute’s element, oldValue, and value.
To append an attribute attribute to an element element, run these steps:
-
Append attribute to element’s attribute list.
-
Set attribute’s element to element.
-
Handle attribute changes for attribute with element, null, and attribute’s value.
To remove an attribute attribute, run these steps:
-
Let element be attribute’s element.
- Remove attribute from element’s attribute list.
-
Set attribute’s element to null.
-
Handle attribute changes for attribute with element, attribute’s value, and null.
To replace an attribute oldAttr with an attribute newAttr, run these steps:
-
Replace oldAttr by newAttr in oldAttr’s element’s attribute list.
-
Set oldAttr’s element to null.
-
Handle attribute changes for oldAttr with newAttr’s element, oldAttr’s value, and newAttr’s value.
To get an attribute by name given a string qualifiedName and an element element:
-
If element is in the HTML namespace and its node document is an HTML document, then set qualifiedName to qualifiedName in ASCII lowercase.
-
Return the first attribute in element’s attribute list whose qualified name is qualifiedName; otherwise null.
To get an attribute by namespace and local name given null or a string namespace, a string localName, and an element element:
-
If namespace is the empty string, then set it to null.
-
Return the attribute in element’s attribute list whose namespace is namespace and local name is localName, if any; otherwise null.
To get an attribute value given an element element, a string localName, and an optional null or string namespace (default null):
-
Let attr be the result of getting an attribute given namespace, localName, and element.
-
If attr is null, then return the empty string.
-
Return attr’s value.
To set an attribute given an attribute attr and an element element:
-
If attr’s element is neither null nor element, throw an "
InUseAttributeError
"DOMException
. -
Let oldAttr be the result of getting an attribute given attr’s namespace, attr’s local name, and element.
-
If oldAttr is attr, return attr.
-
If oldAttr is non-null, then replace oldAttr with attr.
-
Otherwise, append attr to element.
-
Return oldAttr.
To set an attribute value given an element element, a string localName, a string value, an optional null or string prefix (default null), and an optional null or string namespace (default null):
- Let attribute be the result of getting an attribute given namespace, localName, and element.
- If attribute is null, create an attribute whose namespace is namespace, namespace prefix is prefix, local name is localName, value is value, and node document is element’s node document, then append this attribute to element, and then return.
-
Change attribute to value.
To remove an attribute by name given a string qualifiedName and an element element:
-
Let attr be the result of getting an attribute given qualifiedName and element.
-
If attr is non-null, then remove attr.
-
Return attr.
To remove an attribute by namespace and local name given null or a string namespace, a string localName, and an element element:
-
Let attr be the result of getting an attribute given namespace, localName, and element.
-
If attr is non-null, then remove attr.
-
Return attr.
An element can have an associated unique identifier (ID)
Historically elements could have multiple identifiers e.g., by using
the HTML id
attribute and a DTD. This specification makes ID a concept of the DOM and allows for only one per element, given by an id
attribute.
Use these attribute change steps to update an element’s ID:
-
If localName is
id
, namespace is null, and value is null or the empty string, then unset element’s ID. -
Otherwise, if localName is
id
, namespace is null, then set element’s ID to value.
While this specification defines requirements for class
, id
, and slot
attributes on any element, it makes no
claims as to whether using them is conforming or not.
A node’s parent of type Element
is known as its parent element. If the node has a parent of a different type, its parent element is null.
- namespace = element .
namespaceURI
- Returns the namespace.
- prefix = element .
prefix
- Returns the namespace prefix.
- localName = element .
localName
- Returns the local name.
- qualifiedName = element .
tagName
- Returns the HTML-uppercased qualified name.
The namespaceURI
getter steps are to return this’s namespace.
The prefix
getter steps are to return this’s namespace prefix.
The localName
getter steps are to return this’s local name.
The tagName
getter steps are to return this’s HTML-uppercased qualified name.
element . id [ = value ]
-
Returns the value of element’s
id
content attribute. Can be set to change it. element . className [ = value ]
-
Returns the value of element’s
class
content attribute. Can be set to change it. element . classList
-
Allows for manipulation of element’s
class
content attribute as a set of whitespace-separated tokens through aDOMTokenList
object. element . slot [ = value ]
-
Returns the value of element’s
slot
content attribute. Can be set to change it.
IDL attributes that are defined to reflect a string name, must have these getter and setter steps:
- getter steps
-
Return the result of running get an attribute value given this and name.
- setter steps
-
Set an attribute value for this using name and the given value.
The id
attribute must reflect "id
".
The className
attribute must reflect "class
".
The classList
getter steps are to return a DOMTokenList
object whose associated element is this and whose associated attribute’s local name is class
. The token set of this
particular DOMTokenList
object are also known as the element’s classes.
The slot
attribute must reflect "slot
".
id
, class
, and slot
are effectively
superglobal attributes as they can appear on any element, regardless of that element’s
namespace.
element . hasAttributes()
-
Returns true if element has attributes; otherwise false.
element . getAttributeNames()
-
Returns the qualified names of all element’s attributes. Can contain duplicates.
element . getAttribute(qualifiedName)
-
Returns element’s first attribute whose qualified name is qualifiedName, and null if there is no such attribute otherwise.
element . getAttributeNS(namespace, localName)
-
Returns element’s attribute whose namespace is namespace and local name is localName, and null if there is no such attribute otherwise.
element . setAttribute(qualifiedName, value)
-
Sets the value of element’s first attribute whose qualified name is qualifiedName to value.
element . setAttributeNS(namespace, localName, value)
-
Sets the value of element’s attribute whose namespace is namespace and local name is localName to value.
element . removeAttribute(qualifiedName)
-
Removes element’s first attribute whose qualified name is qualifiedName.
element . removeAttributeNS(namespace, localName)
-
Removes element’s attribute whose namespace is namespace and local name is localName.
element . toggleAttribute(qualifiedName [, force])
-
If force is not given, "toggles" qualifiedName, removing it if it is present and adding it if it is not present. If force is true, adds qualifiedName. If force is false, removes qualifiedName.
Returns true if qualifiedName is now present; otherwise false.
element . hasAttribute(qualifiedName)
-
Returns true if element has an attribute whose qualified name is qualifiedName; otherwise false.
element . hasAttributeNS(namespace, localName)
-
Returns true if element has an attribute whose namespace is namespace and local name is localName.
The hasAttributes()
method steps are to return false
if this’s attribute list is empty; otherwise true.
The attributes
getter steps are to return the
associated NamedNodeMap
.
The getAttributeNames()
method steps are to return the qualified names of the attributes in this’s attribute list, in order; otherwise a new list.
These are not guaranteed to be unique.
The getAttribute(qualifiedName)
method
steps are:
-
Let attr be the result of getting an attribute given qualifiedName and this.
-
If attr is null, return null.
-
Return attr’s value.
The getAttributeNS(namespace, localName)
method steps are:
-
Let attr be the result of getting an attribute given namespace, localName, and this.
-
If attr is null, return null.
-
Return attr’s value.
The setAttribute(qualifiedName, value)
method steps are:
-
If qualifiedName does not match the
Name
production in XML, then throw an "InvalidCharacterError
"DOMException
. -
If this is in the HTML namespace and its node document is an HTML document, then set qualifiedName to qualifiedName in ASCII lowercase.
-
Let attribute be the first attribute in this’s attribute list whose qualified name is qualifiedName, and null otherwise.
-
If attribute is null, create an attribute whose local name is qualifiedName, value is value, and node document is this’s node document, then append this attribute to this, and then return.
-
Change attribute to value.
The setAttributeNS(namespace, qualifiedName, value)
method steps are:
-
Let namespace, prefix, and localName be the result of passing namespace and qualifiedName to validate and extract.
-
Set an attribute value for this using localName, value, and also prefix and namespace.
The removeAttribute(qualifiedName)
method steps are to remove an attribute given qualifiedName and this, and then return undefined.
The removeAttributeNS(namespace, localName)
method steps are to remove an attribute given namespace, localName, and this, and then return undefined.
The hasAttribute(qualifiedName)
method
steps are:
-
If this is in the HTML namespace and its node document is an HTML document, then set qualifiedName to qualifiedName in ASCII lowercase.
-
Return true if this has an attribute whose qualified name is qualifiedName; otherwise false.
The toggleAttribute(qualifiedName, force)
method steps are:
-
If qualifiedName does not match the
Name
production in XML, then throw an "InvalidCharacterError
"DOMException
. -
If this is in the HTML namespace and its node document is an HTML document, then set qualifiedName to qualifiedName in ASCII lowercase.
-
Let attribute be the first attribute in this’s attribute list whose qualified name is qualifiedName, and null otherwise.
-
If attribute is null, then:
-
If force is not given or is true, create an attribute whose local name is qualifiedName, value is the empty string, and node document is this’s node document, then append this attribute to this, and then return true.
-
Return false.
-
-
Otherwise, if force is not given or is false, remove an attribute given qualifiedName and this, and then return false.
-
Return true.
The hasAttributeNS(namespace, localName)
method steps are:
-
If namespace is the empty string, then set it to null.
- Return true if this has an attribute whose namespace is namespace and local name is localName; otherwise false.
The getAttributeNode(qualifiedName)
method
steps are to return the result of getting an attribute given qualifiedName and this.
The getAttributeNodeNS(namespace, localName)
method steps are to return the result of getting an attribute given namespace, localName, and this.
The setAttributeNode(attr)
and setAttributeNodeNS(attr)
methods steps are to
return the result of setting an attribute given attr and this.
The removeAttributeNode(attr)
method steps
are:
-
If this’s attribute list does not contain attr, then throw a "
NotFoundError
"DOMException
. -
Remove attr.
-
Return attr.
var shadow = element .
attachShadow(init)
-
Creates a shadow root for element and returns it.
var shadow = element .
shadowRoot
-
Returns element’s shadow root, if any, and if shadow root’s mode is "
open
", and null otherwise.
A valid shadow host name is:
- a valid custom element name
- "
article
", "aside
", "blockquote
", "body
", "div
", "footer
", "h1
", "h2
", "h3
", "h4
", "h5
", "h6
", "header
", "main
", "nav
", "p
", "section
", or "span
"
The attachShadow(init)
method steps are:
-
Run attach a shadow root with this, init["
mode
"], init["clonable
"], init["serializable
"], init["delegatesFocus
"], and init["slotAssignment
"]. -
Return this’s shadow root.
To attach a shadow root, given an element element, a string mode, a boolean clonable, a boolean serializable, a boolean delegatesFocus, and a string slotAssignment:
-
If element’s namespace is not the HTML namespace, then throw a "
NotSupportedError
"DOMException
. -
If element’s local name is not a valid shadow host name, then throw a "
NotSupportedError
"DOMException
. -
If element’s local name is a valid custom element name, or element’s
is
value is non-null, then:-
Let definition be the result of looking up a custom element definition given element’s node document, its namespace, its local name, and its
is
value. -
If definition is not null and definition’s disable shadow is true, then throw a "
NotSupportedError
"DOMException
.
-
-
If element is a shadow host, then:
-
Let currentShadowRoot be element’s shadow root.
-
If any of the following are true:
-
currentShadowRoot’s declarative is false; or
-
currentShadowRoot’s mode is not mode,
then throw a "
NotSupportedError
"DOMException
. -
-
Otherwise:
-
Remove all of currentShadowRoot’s children, in tree order.
-
Set currentShadowRoot’s declarative to false.
-
Return.
-
-
-
Let shadow be a new shadow root whose node document is element’s node document, host is element, and mode is mode.
-
Set shadow’s delegates focus to delegatesFocus.
-
If element’s custom element state is "
precustomized
" or "custom
", then set shadow’s available to element internals to true. -
Set shadow’s slot assignment to slotAssignment.
-
Set shadow’s declarative to false.
-
Set shadow’s clonable to clonable.
-
Set shadow’s serializable to serializable.
-
Set element’s shadow root to shadow.
The shadowRoot
getter steps are:
-
Let shadow be this’s shadow root.
-
If shadow is null or its mode is "
closed
", then return null. -
Return shadow.
element .
closest(selectors)
- Returns the first (starting at element) inclusive ancestor that matches selectors, and null otherwise.
element .
matches(selectors)
- Returns true if matching selectors against element’s root yields element; otherwise false.
The closest(selectors)
method steps are:
-
Let s be the result of parse a selector from selectors. [SELECTORS4]
-
If s is failure, then throw a "
SyntaxError
"DOMException
. -
Let elements be this’s inclusive ancestors that are elements, in reverse tree order.
-
For each element in elements, if match a selector against an element, using s, element, and scoping root this, returns success, return element. [SELECTORS4]
-
Return null.
The matches(selectors)
and webkitMatchesSelector(selectors)
method steps
are:
-
Let s be the result of parse a selector from selectors. [SELECTORS4]
-
If s is failure, then throw a "
SyntaxError
"DOMException
. -
If the result of match a selector against an element, using s, this, and scoping root this, returns success, then return true; otherwise, return false. [SELECTORS4]
The getElementsByTagName(qualifiedName)
method steps are to return the list of elements with qualified name qualifiedName for this.
The getElementsByTagNameNS(namespace, localName)
method steps are to return the list of elements with namespace namespace and local
name localName for this.
The getElementsByClassName(classNames)
method steps are to return the list of elements with class names classNames for this.
To insert adjacent, given an element element, string where, and a node node, run the steps associated with the first ASCII case-insensitive match for where:
- "
beforebegin
" -
If element’s parent is null, return null.
Return the result of pre-inserting node into element’s parent before element.
- "
afterbegin
" -
Return the result of pre-inserting node into element before element’s first child.
- "
beforeend
" -
Return the result of pre-inserting node into element before null.
- "
afterend
" -
If element’s parent is null, return null.
Return the result of pre-inserting node into element’s parent before element’s next sibling.
- Otherwise
-
Throw a "
SyntaxError
"DOMException
.
The insertAdjacentElement(where, element)
method steps are to return the result of running insert adjacent, give this, where, and element.
The insertAdjacentText(where, data)
method steps are:
-
Let text be a new
Text
node whose data is data and node document is this’s node document. -
Run insert adjacent, given this, where, and text.
This method returns nothing because it existed before we had a chance to design it.
4.9.1. Interface NamedNodeMap
[Exposed =Window ,LegacyUnenumerableNamedProperties ]interface {
NamedNodeMap readonly attribute unsigned long length ;getter Attr ?item (unsigned long );
index getter Attr ?getNamedItem (DOMString );
qualifiedName Attr ?getNamedItemNS (DOMString ?,
namespace DOMString ); [
localName CEReactions ]Attr ?setNamedItem (Attr ); [
attr CEReactions ]Attr ?setNamedItemNS (Attr ); [
attr CEReactions ]Attr removeNamedItem (DOMString ); [
qualifiedName CEReactions ]Attr removeNamedItemNS (DOMString ?,
namespace DOMString ); };
localName
A NamedNodeMap
has an associated element (an element).
A NamedNodeMap
object’s attribute list is its element’s attribute list.
A NamedNodeMap
object’s supported property indices are the numbers in the
range zero to its attribute list’s size minus one, unless
the attribute list is empty, in which case there are no supported property indices.
The length
getter steps are to return
the attribute list’s size.
The item(index)
method steps are:
-
If index is equal to or greater than this’s attribute list’s size, then return null.
-
Otherwise, return this’s attribute list[index].
A NamedNodeMap
object’s supported property names are the return value of running these
steps:
-
Let names be the qualified names of the attributes in this
NamedNodeMap
object’s attribute list, with duplicates omitted, in order. -
If this
NamedNodeMap
object’s element is in the HTML namespace and its node document is an HTML document, then for each name in names:-
Let lowercaseName be name, in ASCII lowercase.
-
If lowercaseName is not equal to name, remove name from names.
-
-
Return names.
The getNamedItem(qualifiedName)
method steps are to return the result of getting an attribute given qualifiedName and element.
The getNamedItemNS(namespace, localName)
method steps are to return the result of getting an attribute given namespace, localName, and element.
The setNamedItem(attr)
and setNamedItemNS(attr)
method steps are
to return the result of setting an attribute given attr and element.
The removeNamedItem(qualifiedName)
method steps are:
-
Let attr be the result of removing an attribute given qualifiedName and element.
-
If attr is null, then throw a "
NotFoundError
"DOMException
. -
Return attr.
The removeNamedItemNS(namespace, localName)
method steps are:
-
Let attr be the result of removing an attribute given namespace, localName, and element.
-
If attr is null, then throw a "
NotFoundError
"DOMException
. -
Return attr.
4.9.2. Interface Attr
[Exposed =Window ]interface :
Attr Node {readonly attribute DOMString ?namespaceURI ;readonly attribute DOMString ?prefix ;readonly attribute DOMString localName ;readonly attribute DOMString name ; [CEReactions ]attribute DOMString value ;readonly attribute Element ?ownerElement ;readonly attribute boolean specified ; // useless; always returns true };
Attr
nodes are simply known as attributes. They are sometimes referred
to as content attributes to avoid confusion with IDL attributes.
Attributes have a namespace (null or a non-empty string), namespace prefix (null or a non-empty string), local name (a non-empty string), value (a string), and element (null or an element).
If designed today they would just have a name and value. ☹
An attribute’s qualified name is its local name if its namespace prefix is null, and its namespace prefix, followed by ":
", followed by its local name, otherwise.
User agents could have this as an internal slot as an optimization.
When an attribute is created, its local name is given. Unless explicitly given when an attribute is created, its namespace, namespace prefix, and element are set to null, and its value is set to the empty string.
An A
attribute is an attribute whose local name is A
and whose namespace and namespace prefix are
null.
The namespaceURI
getter steps are to return this’s namespace.
The prefix
getter steps are to return this’s namespace prefix.
The localName
getter steps are to return this’s local name.
The name
getter steps are to return this’s qualified name.
The value
getter steps are to return this’s value.
To set an existing attribute value, given an attribute attribute and string value, run these steps:
-
If attribute’s element is null, then set attribute’s value to value.
-
Otherwise, change attribute to value.
The value
setter steps are to set an existing attribute value with this and the given value.
The ownerElement
getter steps are to return this’s element.
The specified
getter steps are to return true.
4.10. Interface CharacterData
[Exposed =Window ]interface :
CharacterData Node {attribute [LegacyNullToEmptyString ]DOMString data ;readonly attribute unsigned long length ;DOMString substringData (unsigned long ,
offset unsigned long );
count undefined appendData (DOMString );
data undefined insertData (unsigned long ,
offset DOMString );
data undefined deleteData (unsigned long ,
offset unsigned long );
count undefined replaceData (unsigned long ,
offset unsigned long ,
count DOMString ); };
data
CharacterData
is an abstract interface. You cannot get a direct instance of it. It
is used by Text
, ProcessingInstruction
, and Comment
nodes.
Each node inheriting from the CharacterData
interface has an associated mutable
string called data.
To replace data of node node with offset offset, count count, and data data, run these steps:
- Let length be node’s length.
- If offset is greater than length, then throw an
"
IndexSizeError
"DOMException
. - If offset plus count is greater than length, then set count to length minus offset.
-
Queue a mutation record of "
characterData
" for node with null, null, node’s data, « », « », null, and null. - Insert data into node’s data after offset code units.
- Let delete offset be offset + data’s length.
- Starting from delete offset code units, remove count code units from node’s data.
-
For each live range whose start node is node and start offset is greater than offset but less than or equal to offset plus count, set its start offset to offset.
-
For each live range whose end node is node and end offset is greater than offset but less than or equal to offset plus count, set its end offset to offset.
-
For each live range whose start node is node and start offset is greater than offset plus count, increase its start offset by data’s length and decrease it by count.
-
For each live range whose end node is node and end offset is greater than offset plus count, increase its end offset by data’s length and decrease it by count.
-
If node’s parent is non-null, then run the children changed steps for node’s parent.
To substring data with node node, offset offset, and count count, run these steps:
- Let length be node’s length.
- If offset is greater than length, then throw an
"
IndexSizeError
"DOMException
. - If offset plus count is greater than length, return a string whose value is the code units from the offsetth code unit to the end of node’s data, and then return.
- Return a string whose value is the code units from the offsetth code unit to the offset+countth code unit in node’s data.
The data
getter steps are to return this’s data. Its setter must replace data with node this, offset 0, count this’s length, and data new value.
The length
getter steps are to return this’s length.
The substringData(offset, count)
method steps are to return the result of running substring data with node this,
offset offset, and count count.
The appendData(data)
method steps are
to replace data with node this, offset this’s length, count 0,
and data data.
The insertData(offset, data)
method steps are to replace data with node this, offset offset, count 0,
and data data.
The deleteData(offset, count)
method steps are to replace data with node this, offset offset, count count, and data the empty string.
The replaceData(offset, count, data)
method steps are to replace data with node this, offset offset, count count, and data data.
4.11. Interface Text
[Exposed =Window ]interface :
Text CharacterData {constructor (optional DOMString = ""); [
data NewObject ]Text splitText (unsigned long );
offset readonly attribute DOMString wholeText ; };
text = new Text([data = ""])
- Returns a new
Text
node whose data is data. text .
splitText(offset)
- Splits data at the given offset and returns the remainder as
Text
node. text .
wholeText
- Returns the combined data of all direct
Text
node siblings.
An exclusive Text
node is a Text
node that is not a CDATASection
node.
The contiguous Text
nodes of a node node are node, node’s previous sibling Text
node, if any, and
its contiguous Text
nodes, and node’s next sibling Text
node, if any, and its contiguous Text
nodes, avoiding any
duplicates.
The contiguous exclusive Text
nodes of a node node are node, node’s previous sibling exclusive Text
node, if any, and its contiguous exclusive Text
nodes, and node’s next sibling exclusive Text
node, if any, and its contiguous exclusive Text
nodes, avoiding any duplicates.
The child text content of a node node is the concatenation of the data of all
the Text
node children of node, in tree order.
The descendant text content of a node node is the concatenation of the data of all the Text
node descendants of node, in tree order.
The new Text(data)
constructor steps are to set this’s data to data and this’s node document to current global object’s associated Document
.
To split a Text
node node with offset offset, run these steps:
- Let length be node’s length.
- If offset is greater than length, then throw an
"
IndexSizeError
"DOMException
. - Let count be length minus offset.
- Let new data be the result of substringing data with node node, offset offset, and count count.
- Let new node be a new
Text
node, with the same node document as node. Set new node’s data to new data. - Let parent be node’s parent.
-
If parent is not null, then:
-
Insert new node into parent before node’s next sibling.
-
For each live range whose start node is node and start offset is greater than offset, set its start node to new node and decrease its start offset by offset.
-
For each live range whose end node is node and end offset is greater than offset, set its end node to new node and decrease its end offset by offset.
-
For each live range whose start node is parent and start offset is equal to the index of node plus 1, increase its start offset by 1.
-
For each live range whose end node is parent and end offset is equal to the index of node plus 1, increase its end offset by 1.
-
- Replace data with node node, offset offset, count count, and data the empty string.
- Return new node.
The splitText(offset)
method steps are to split this with offset offset.
The wholeText
getter steps are to return the concatenation of the data of the contiguous Text
nodes of this, in tree order.
4.12. Interface CDATASection
[Exposed =Window ]interface :
CDATASection Text { };
4.13. Interface ProcessingInstruction
[Exposed =Window ]interface :
ProcessingInstruction CharacterData {readonly attribute DOMString target ; };
ProcessingInstruction
nodes have an associated target.
The target
getter steps are to return this’s target.
4.14. Interface Comment
[Exposed =Window ]interface :
Comment CharacterData {constructor (optional DOMString = ""); };
data
comment = new Comment([data = ""])
- Returns a new
Comment
node whose data is data.
The new Comment(data)
constructor steps are to set this’s data to data and this’s node document to current global object’s associated Document
.
5. Ranges
5.1. Introduction to "DOM Ranges"
StaticRange
and Range
objects (ranges) represent a sequence of content within a node tree. Each range has a start and an end which
are boundary points. A boundary point is a tuple consisting of a node and an offset. So in other words, a range represents a piece of content within a node tree between two boundary points.
Ranges are frequently used in editing for selecting and copying content.
-
Element
:p
In the node tree above, a range can be used to represent the sequence
“syndata is awes”. Assuming p is assigned to the p
element, and em to the em
element, this would be done as follows:
var range = new Range(),
firstText = p. childNodes[ 1 ],
secondText = em. firstChild
range. setStart( firstText, 9 ) // do not forget the leading space
range. setEnd( secondText, 4 )
// range now stringifies to the aforementioned quote
Attributes such as src
and alt
in the node tree above cannot be represented by a range. Ranges are only useful for nodes.
Range
objects, unlike StaticRange
objects, are affected by mutations to the node tree. Therefore they are also known as live ranges. Such mutations will not
invalidate them and will try to ensure that it still represents the same piece of content.
Necessarily, a live range might itself be modified as part of the mutation to the node tree when, e.g., part of the content it represents is mutated.
See the insert and remove algorithms, the normalize()
method, and the replace data and split algorithms for details.
Updating live ranges in response to node tree mutations can be expensive. For every node tree change, all affected Range
objects need to be updated. Even if the application
is uninterested in some live ranges, it still has to pay the cost of keeping them up-to-date
when a mutation occurs.
A StaticRange
object is a lightweight range that does not update when the node tree mutates. It is therefore not subject to the same maintenance cost as live ranges.
5.2. Boundary points
A boundary point is a tuple consisting of a node (a node) and an offset (a non-negative integer).
A correct boundary point’s offset will be between 0 and the boundary point’s node’s length, inclusive.
The position of a boundary point (nodeA, offsetA) relative to a boundary point (nodeB, offsetB) is before, equal, or after, as returned by these steps:
-
Assert: nodeA and nodeB have the same root.
- If nodeA is nodeB, then return equal if offsetA is offsetB, before if offsetA is less than offsetB, and after if offsetA is greater than offsetB.
-
If nodeA is following nodeB, then if the position of (nodeB, offsetB) relative to (nodeA, offsetA) is before, return after, and if it is after, return before.
-
If nodeA is an ancestor of nodeB:
-
Return before.
5.3. Interface AbstractRange
[Exposed =Window ]interface {
AbstractRange readonly attribute Node startContainer ;readonly attribute unsigned long startOffset ;readonly attribute Node endContainer ;readonly attribute unsigned long endOffset ;readonly attribute boolean collapsed ; };
Objects implementing the AbstractRange
interface are known as ranges.
A range has two associated boundary points — a start and end.
For convenience, a range’s start node is its start’s node, its start offset is its start’s offset, its end node is its end’s node, and its end offset is its end’s offset.
A range is collapsed if its start node is its end node and its start offset is its end offset.
node = range . startContainer
- Returns range’s start node.
offset = range . startOffset
- Returns range’s start offset.
node = range . endContainer
- Returns range’s end node.
offset = range . endOffset
- Returns range’s end offset.
collapsed = range . collapsed
- Returns true if range is collapsed; otherwise false.
The startContainer
getter steps are to return this’s start node.
The startOffset
getter steps are to return this’s start offset.
The endContainer
getter steps are to return this’s end node.
The endOffset
getter steps are to return this’s end offset.
The collapsed
getter steps are to return true if this is collapsed; otherwise false.
5.4. Interface StaticRange
dictionary {
StaticRangeInit required Node ;
startContainer required unsigned long ;
startOffset required Node ;
endContainer required unsigned long ; }; [
endOffset Exposed =Window ]interface :
StaticRange AbstractRange {constructor (StaticRangeInit ); };
init
staticRange = new StaticRange(init)
-
Returns a new range object that does not update when the node tree mutates.
The new StaticRange(init)
constructor steps are:
-
If init["
startContainer
"] or init["endContainer
"] is aDocumentType
orAttr
node, then throw an "InvalidNodeTypeError
"DOMException
. -
Set this’s start to (init["
startContainer
"], init["startOffset
"]) and end to (init["endContainer
"], init["endOffset
"]).
A StaticRange
is valid if all of the following are true:
-
Its start offset is between 0 and its start node’s length, inclusive.
-
Its end offset is between 0 and its end node’s length, inclusive.
5.5. Interface Range
[Exposed =Window ]interface :
Range AbstractRange {constructor ();readonly attribute Node commonAncestorContainer ;undefined setStart (Node ,
node unsigned long );
offset undefined setEnd (Node ,
node unsigned long );
offset undefined setStartBefore (Node );
node undefined setStartAfter (Node );
node undefined setEndBefore (Node );
node undefined setEndAfter (Node );
node undefined collapse (optional boolean =
toStart false );undefined selectNode (Node );
node undefined selectNodeContents (Node );
node const unsigned short = 0;
START_TO_START const unsigned short = 1;
START_TO_END const unsigned short = 2;
END_TO_END const unsigned short = 3;
END_TO_START short compareBoundaryPoints (unsigned short ,
how Range ); [
sourceRange CEReactions ]undefined deleteContents (); [CEReactions ,NewObject ]DocumentFragment extractContents (); [CEReactions ,NewObject ]DocumentFragment cloneContents (); [CEReactions ]undefined insertNode (Node ); [
node CEReactions ]undefined surroundContents (Node ); [
newParent NewObject ]Range cloneRange ();undefined detach ();boolean isPointInRange (Node ,
node unsigned long );
offset short comparePoint (Node ,
node unsigned long );
offset boolean intersectsNode (Node );
node stringifier ; };
Objects implementing the Range
interface are known as live ranges.
Algorithms that modify a tree (in particular the insert, remove, replace data, and split algorithms) modify live ranges associated with that tree.
The root of a live range is the root of its start node.
A node node is contained in a live range range if node’s root is range’s root, and (node, 0) is after range’s start, and (node, node’s length) is before range’s end.
A node is partially contained in a live range if it’s an inclusive ancestor of the live range’s start node but not its end node, or vice versa.
Some facts to better understand these definitions:
-
The content that one would think of as being within the live range consists of all contained nodes, plus possibly some of the contents of the start node and end node if those are
CharacterData
nodes. -
The nodes that are contained in a live range will generally not be contiguous, because the parent of a contained node will not always be contained.
-
However, the descendants of a contained node are contained, and if two siblings are contained, so are any siblings that lie between them.
-
The start node and end node of a live range are never contained within it.
-
The first contained node (if there are any) will always be after the start node, and the last contained node will always be equal to or before the end node’s last descendant.
-
There exists a partially contained node if and only if the start node and end node are different.
-
The
commonAncestorContainer
attribute value is neither contained nor partially contained. -
If the start node is an ancestor of the end node, the common inclusive ancestor will be the start node. Exactly one of its children will be partially contained, and a child will be contained if and only if it precedes the partially contained child. If the end node is an ancestor of the start node, the opposite holds.
-
If the start node is not an inclusive ancestor of the end node, nor vice versa, the common inclusive ancestor will be distinct from both of them. Exactly two of its children will be partially contained, and a child will be contained if and only if it lies between those two.
range = new Range()
- Returns a new live range.
The new Range()
constructor steps are
to set this’s start and end to
(current global object’s associated Document
, 0).
- container = range .
commonAncestorContainer
- Returns the node, furthest away from the document, that is an ancestor of both range’s start node and end node.
The commonAncestorContainer
getter steps are:
- Let container be start node.
- While container is not an inclusive ancestor of end node, let container be container’s parent.
- Return container.
To set the start or end of a range to a boundary point (node, offset), run these steps:
- If node is a doctype, then throw an
"
InvalidNodeTypeError
"DOMException
. - If offset is greater than node’s length, then throw an "
IndexSizeError
"DOMException
. - Let bp be the boundary point (node, offset).
-
- If these steps were invoked as "set the start"
- If these steps were invoked as "set the end"
The setStart(node, offset)
method
steps are to set the start of this to boundary point (node, offset).
The setEnd(node, offset)
method
steps are to set the end of this to boundary point (node, offset).
The setStartBefore(node)
method steps are:
- Let parent be node’s parent.
- If parent is null, then throw an "
InvalidNodeTypeError
"DOMException
. - Set the start of this to boundary point (parent, node’s index).
The setStartAfter(node)
method steps are:
-
Let parent be node’s parent.
-
If parent is null, then throw an "
InvalidNodeTypeError
"DOMException
. -
Set the start of this to boundary point (parent, node’s index plus 1).
The setEndBefore(node)
method steps are:
- Let parent be node’s parent.
- If parent is null, then throw an "
InvalidNodeTypeError
"DOMException
. - Set the end of this to boundary point (parent, node’s index).
The setEndAfter(node)
method steps are:
-
Let parent be node’s parent.
-
If parent is null, then throw an "
InvalidNodeTypeError
"DOMException
. -
Set the end of this to boundary point (parent, node’s index plus 1).
The collapse(toStart)
method steps are to, if toStart is true, set end to start; otherwise set start to end.
To select a node node within a range range, run these steps:
-
Let parent be node’s parent.
-
If parent is null, then throw an "
InvalidNodeTypeError
"DOMException
. -
Let index be node’s index.
-
Set range’s start to boundary point (parent, index).
-
Set range’s end to boundary point (parent, index plus 1).
The selectNode(node)
method steps are to select node within this.
The selectNodeContents(node)
method steps
are:
-
If node is a doctype, throw an "
InvalidNodeTypeError
"DOMException
. -
Let length be the length of node.
-
Set start to the boundary point (node, 0).
-
Set end to the boundary point (node, length).
The compareBoundaryPoints(how, sourceRange)
method steps are:
-
If how is not one of
then throw a "
NotSupportedError
"DOMException
. - If this’s root is not the same as sourceRange’s root, then throw a "
WrongDocumentError
"DOMException
. -
If how is:
START_TO_START
:- Let this point be this’s start. Let other point be sourceRange’s start.
START_TO_END
:- Let this point be this’s end. Let other point be sourceRange’s start.
END_TO_END
:- Let this point be this’s end. Let other point be sourceRange’s end.
END_TO_START
:- Let this point be this’s start. Let other point be sourceRange’s end.
-
If the position of this point relative to other point is
The deleteContents()
method steps are:
- Let original start node, original start offset, original end node, and original end offset be this’s start node, start offset, end node, and end offset, respectively.
-
If original start node is original end node and it is a
CharacterData
node, then replace data with node original start node, offset original start offset, count original end offset minus original start offset, and data the empty string, and then return. - Let nodes to remove be a list of all the nodes that are contained in this, in tree order, omitting any node whose parent is also contained in this.
- If original start node is an inclusive ancestor of original end node, set new node to original start node and new offset to original start offset.
-
Otherwise:
- Let reference node equal original start node.
- While reference node’s parent is not null and is not an inclusive ancestor of original end node, set reference node to its parent.
- Set new node to the parent of reference node, and new offset to one plus the