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CustomEvent
interface represents events initialized by an application for any purpose.
Constructor
CustomEvent()
- Creates a
CustomEvent
.
Properties
CustomEvent.detail
Read only- Any data passed when initializing the event.
This interface inherits properties from its parent, Event
:
Event.bubbles
Read only- A Boolean indicating whether the event bubbles up through the DOM or not.
Event.cancelBubble
- A historical alias to
Event.stopPropagation()
. Setting its value totrue
before returning from an event handler prevents propagation of the event. Event.cancelable
Read only- A Boolean indicating whether the event is cancelable.
Event.composed
Read only- A Boolean value indicating whether or not the event can bubble across the boundary between the shadow DOM and the regular DOM.
Event.currentTarget
Read only- A reference to the currently registered target for the event. This is the object to which the event is currently slated to be sent; it's possible this has been changed along the way through retargeting.
Event.deepPath
- An
Array
of DOMNode
s through which the event has bubbled. Event.defaultPrevented
Read only- Indicates whether or not
event.preventDefault()
has been called on the event. Event.eventPhase
Read only- Indicates which phase of the event flow is being processed.
Event.explicitOriginalTarget
Read only- The explicit original target of the event (Mozilla-specific).
Event.originalTarget
Read only- The original target of the event, before any retargetings (Mozilla-specific).
Event.returnValue
- A historical property introduced by Internet Explorer and eventually adopted into the DOM specification in order to ensure existing sites continue to work. Ideally, you should try to use
Event.preventDefault()
andEvent.defaultPrevented
instead, but you can usereturnValue
if you choose to do so. Event.srcElement
- A non-standard alias (from old versions of Microsoft Internet Explorer) for
Event.target
, which is starting to be supported in some other browsers for web compatibility purposes. Event.target
Read only- A reference to the target to which the event was originally dispatched.
Event.timeStamp
Read only- The time at which the event was created (in milliseconds). By specification, this value is time since epoch, but in reality browsers' definitions vary; in addition, work is underway to change this to be a
DOMHighResTimeStamp
instead. Event.type
Read only- The name of the event (case-insensitive).
Event.isTrusted
Read only- Indicates whether or not the event was initiated by the browser (after a user click for instance) or by a script (using an event creation method, like event.initEvent).
Obsolete properties
Event.scoped
Read only- A
Boolean
indicating whether the given event will bubble across through the shadow root into the standard DOM. This property has been renamed tocomposed
.
Methods
CustomEvent.initCustomEvent()
-
Initializes a
CustomEvent
object. If the event has already being dispatched, this method does nothing.
This interface inherits methods from its parent, Event
:
Event.createEvent()
-
Creates a new event, which must then be initialized by calling its
initEvent()
method. Event.composedPath()
- Returns the event’s path (objects on which listeners will be invoked). This does not include nodes in shadow trees if the shadow root was created with its
ShadowRoot.mode
closed.
Event.initEvent()
- Initializes the value of an Event created. If the event has already being dispatched, this method does nothing.
Event.preventDefault()
- Cancels the event (if it is cancelable).
Event.stopImmediatePropagation()
- For this particular event, no other listener will be called. Neither those attached on the same element, nor those attached on elements which will be traversed later (in capture phase, for instance)
Event.stopPropagation()
- Stops the propagation of events further along in the DOM.
Obsolete methods
Event.getPreventDefault()
- Non-standard. Returns the value of
Event.defaultPrevented
. UseEvent.defaultPrevented
instead. Event.preventBubble()
Obsolete since Gecko 24- Prevents the event from bubbling. Obsolete, use
event.stopPropagation
instead. Event.preventCapture()
Obsolete since Gecko 24- Obsolete, use
event.stopPropagation
instead.
Specifications
Specification | Status | Comment |
---|---|---|
DOM The definition of 'CustomEvent' in that specification. |
Living Standard | Initial definition. |
Browser compatibility
Desktop | Mobile | ||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Basic support | Chrome Full support Yes | Edge Full support Yes | Firefox Full support 6 | IE Full support 9 | Opera Full support 11 | Safari Full support 5.1 | WebView Android Full support Yes | Chrome Android Full support Yes | Edge Mobile Full support Yes | Firefox Android Full support Yes | Opera Android Full support Yes | Safari iOS Full support Yes | Samsung Internet Android ? |
Available in workers | Chrome Full support Yes | Edge Full support Yes | Firefox Full support 48 | IE Full support Yes | Opera Full support Yes | Safari Full support Yes | WebView Android Full support Yes | Chrome Android Full support Yes | Edge Mobile Full support Yes | Firefox Android Full support 48 | Opera Android Full support Yes | Safari iOS Full support Yes | Samsung Internet Android ? |
CustomEvent() constructor | Chrome Full support 15 | Edge Full support Yes | Firefox Full support 11 | IE No support No | Opera Full support 11.6 | Safari
No support
No
| WebView Android Full support Yes | Chrome Android Full support Yes | Edge Mobile Full support Yes | Firefox Android Full support Yes | Opera Android Full support Yes | Safari iOS
No support
No
| Samsung Internet Android ? |
detail | Chrome Full support 11 | Edge ? | Firefox Full support 11 | IE No support No | Opera Full support 11.6 | Safari
No support
No
| WebView Android Full support Yes | Chrome Android Full support Yes | Edge Mobile ? | Firefox Android Full support 14 | Opera Android Full support Yes | Safari iOS
No support
No
| Samsung Internet Android ? |
initCustomEvent | Chrome
Full support
Yes
| Edge Full support Yes | Firefox Full support 6 | IE Full support 9 | Opera Full support 11 | Safari Full support 5.1 | WebView Android
Full support
Yes
| Chrome Android
Full support
Yes
| Edge Mobile Full support Yes | Firefox Android Full support 6 | Opera Android Full support Yes | Safari iOS Full support Yes | Samsung Internet Android ? |
Legend
- Full support
- Full support
- No support
- No support
- Compatibility unknown
- Compatibility unknown
- Deprecated. Not for use in new websites.
- Deprecated. Not for use in new websites.
- See implementation notes.
- See implementation notes.
Firing from privileged code to non-privileged code
When firing a CustomEvent from privileged code (i.e. an extension) to non-privileged code (i.e. a webpage), security issues should be considered. Firefox and other Gecko applications restrict an object created in one context from being directly used for another, which will automatically prevent security holes, but these restrictions may also prevent your code from running as expected.
While creating a CustomEvent object, you must create the object from the same window. The detail
attribute of your CustomEvent will be subjected to the same restrictions. String and Array values will be readable by the content without restrictions, but custom Objects will not. While using a custom Object, you will need to define the attributes of that object that are readable from the content script using Components.utils.cloneInto().
// doc is a reference to the content document function dispatchCustomEvent(doc) { var eventDetail = Components.utils.cloneInto({foo: 'bar'}, doc.defaultView); var myEvent = doc.defaultView.CustomEvent("mytype", eventDetail); doc.dispatchEvent(myEvent); }
But one needs to keep in mind that exposing a function will allow the content script to run it with chrome privileges, which can open a security vulnerability.