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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.

Constructor

EventTarget()
Creates a new EventTarget object instance.

Methods

EventTarget.addEventListener()
Registers an event handler of a specific event type on the EventTarget.
EventTarget.removeEventListener()
Removes an event listener from the EventTarget.
EventTarget.dispatchEvent()
Dispatches 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;
    }
  }
};

EventTarget.prototype.dispatchEvent = function(event) {
  if (!(event.type in this.listeners)) {
    return true;
  }
  var stack = this.listeners[event.type].slice();

  for (var i = 0, l = stack.length; i < l; i++) {
    stack[i].call(this, event);
  }
  return !event.defaultPrevented;
};

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

Update compatibility data on GitHub
DesktopMobile
ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidEdge MobileFirefox for AndroidOpera for AndroidiOS SafariSamsung Internet
Basic supportChrome Full support 1Edge Full support YesFirefox Full support 1IE Full support 9Opera Full support 7Safari Full support 10.1
Full support 10.1
No support 1 — 10.1
Notes
Notes Window.EventTarget did not exist on versions of Safari before 10.1.
WebView Android Full support 1Chrome Android Full support 18Edge Mobile Full support YesFirefox Android Full support 4Opera Android Full support 7Safari iOS Full support 10.1
Full support 10.1
No support 1 — 10.1
Notes
Notes Window.EventTarget did not exist on versions of Safari iOS before 10.1.
Samsung Internet Android Full support Yes
EventTarget() constructorChrome Full support 64Edge ? Firefox Full support 59IE No support NoOpera Full support 51Safari No support NoWebView Android Full support 64Chrome Android Full support 64Edge Mobile ? Firefox Android Full support 59Opera Android Full support 51Safari iOS No support NoSamsung Internet Android No support No
addEventListenerChrome Full support 1
Notes
Full support 1
Notes
Notes Before Chrome 49, the type and listener parameters were optional.
Edge Full support 12Firefox Full support 1IE Full support 9
Full support 9
No support 6 — 11
Notes Alternate Name
Notes Older versions of IE supported an equivalent, proprietary EventTarget.attachEvent() method.
Alternate Name Uses the non-standard name: attachEvent
Opera Full support 7Safari Full support 1WebView Android Full support 1
Notes
Full support 1
Notes
Notes Before Chrome 49, the type and listener parameters were optional.
Chrome Android Full support 18
Notes
Full support 18
Notes
Notes Before Chrome 49, the type and listener parameters were optional.
Edge Mobile Full support YesFirefox Android Full support 4Opera Android Full support 7Safari iOS Full support 1Samsung Internet Android Full support Yes
dispatchEventChrome Full support 4Edge Full support 12Firefox Full support 2IE Full support 9
Full support 9
No support 6 — 11
Notes Alternate Name
Notes Older versions of IE supported an equivalent, proprietary EventTarget.fireEvent() method.
Alternate Name Uses the non-standard name: fireEvent
Opera Full support 9Safari Full support 3.2WebView Android Full support 4Chrome Android Full support 18Edge Mobile Full support YesFirefox Android Full support 4Opera Android Full support YesSafari iOS Full support YesSamsung Internet Android Full support Yes
removeEventListenerChrome Full support 1Edge Full support 12Firefox Full support 1IE Full support 9
Full support 9
No support 6 — 11
Notes Alternate Name
Notes Older versions of IE supported an equivalent, proprietary EventTarget.detachEvent() method.
Alternate Name Uses the non-standard name: detachEvent
Opera Full support 7Safari Full support 1WebView Android Full support 1Chrome Android Full support 18Edge Mobile Full support YesFirefox Android Full support 4Opera Android Full support 7Safari iOS Full support 1Samsung Internet Android Full support Yes

Legend

Full support  
Full support
No support  
No support
Compatibility unknown  
Compatibility unknown
See implementation notes.
See implementation notes.
Uses a non-standard name.
Uses a non-standard name.

 

See Also