EventTarget
is an interface implemented by objects that can receive events and may have listeners for them.
Element
, document
, and window
are the most common event targets, but other objects can be event targets too, for example XMLHttpRequest
, AudioNode
, AudioContext
, and others.
Many event targets (including elements, documents, and windows) also support setting event handlers via on...
properties and attributes.
Methods
EventTarget.addEventListener()
- Register an event handler of a specific event type on the
EventTarget
. EventTarget.removeEventListener()
- Removes an event listener from the
EventTarget
. EventTarget.dispatchEvent()
- Dispatch an event to this
EventTarget
.
Additional methods for Mozilla chrome code
Mozilla extensions for use by JS-implemented event targets to implement on* properties. See also WebIDL bindings.
- void setEventHandler(DOMString type, EventHandler handler)
- EventHandler getEventHandler(DOMString type)
Example:
Simple implementation of EventTarget
var EventTarget = function() {
this.listeners = {};
};
EventTarget.prototype.listeners = null;
EventTarget.prototype.addEventListener = function(type, callback) {
if(!(type in this.listeners)) {
this.listeners[type] = [];
}
this.listeners[type].push(callback);
};
EventTarget.prototype.removeEventListener = function(type, callback) {
if(!(type in this.listeners)) {
return;
}
var stack = this.listeners[type];
for(var i = 0, l = stack.length; i < l; i++) {
if(stack[i] === callback){
stack.splice(i, 1);
return this.removeEventListener(type, callback);
}
}
};
EventTarget.prototype.dispatchEvent = function(event) {
if(!(event.type in this.listeners)) {
return;
}
var stack = this.listeners[event.type];
event.target = this;
for(var i = 0, l = stack.length; i < l; i++) {
stack[i].call(this, event);
}
};
Specifications
Specification | Status | Comment |
---|---|---|
DOM The definition of 'EventTarget' in that specification. |
Living Standard | No change. |
Document Object Model (DOM) Level 3 Events Specification The definition of 'EventTarget' in that specification. |
Obsolete | A few parameters are now optional (listener ), or accepts the null value (useCapture ). |
Document Object Model (DOM) Level 2 Events Specification The definition of 'EventTarget' in that specification. |
Obsolete | Initial definition. |
Browser compatibility
We're converting our compatibility data into a machine-readable JSON format.
This compatibility table still uses the old format,
because we haven't yet converted the data it contains.
Find out how you can help!
Feature | Chrome | Firefox (Gecko) | Internet Explorer | Opera | Safari (WebKit) |
---|---|---|---|---|---|
Basic support | 1.0 | 1.0 (1.7 or earlier) | 9.0 | 7 | 1.0[1] |
Feature | Android | Firefox Mobile (Gecko) | IE Mobile | Opera Mobile | Safari Mobile |
---|---|---|---|---|---|
Basic support | 1.0 | 1.0 (1) | 9.0 | 6.0 | 1.0 |
[1] window.EventTarget
does not exist.
See Also
- Event reference - the events available in the platform.
- Event developer guide
Event
interface