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---
title: EventTarget
slug: Web/API/EventTarget
tags:
- API
- DOM
- DOM Events
- Interface
translation_of: Web/API/EventTarget
---
<p>{{ApiRef("DOM Events")}}</p>
<p><code>EventTarget</code> 是一个 DOM 接口，由可以接收事件、并且可以创建侦听器的对象实现。</p>
<p>{{domxref("Element")}}，{{domxref("document")}} 和 {{domxref("window")}} 是最常见的 event targets ，但是其他对象也可以作为 event targets，比如 {{domxref("XMLHttpRequest")}}，{{domxref("AudioNode")}}，{{domxref("AudioContext")}} 等等。</p>
<p>许多 event targets （包括 elements， documents 和 windows）支持通过 <code>onevent</code> 特性和属性设置<a href="/zh-CN/docs/Web/Guide/DOM/Events/Event_handlers">事件处理程序</a> (<a href="https://wiki.developer.mozilla.org/en-US/docs/Web/Guide/DOM/Events/Event_handlers">event handlers</a>)。</p>
<p>{{InheritanceDiagram}}</p>
<h2 id="构造函数">构造函数</h2>
<dl>
<dt>{{domxref("EventTarget.EventTarget()","EventTarget()")}}</dt>
<dd>创建一个新的 <code>EventTarget</code> 对象实例。</dd>
</dl>
<h2 id="Methods" name="Methods">方法</h2>
<dl>
<dt>{{domxref("EventTarget.addEventListener()")}}</dt>
<dd>在EventTarget上注册特定事件类型的事件处理程序。</dd>
<dt>{{domxref("EventTarget.removeEventListener()")}}</dt>
<dd>EventTarget中删除事件侦听器。</dd>
<dt>{{domxref("EventTarget.dispatchEvent()")}}</dt>
<dd>将事件分派到此EventTarget。</dd>
</dl>
<h3 id="Mozilla_chrome_代码的其他方法">Mozilla chrome 代码的其他方法</h3>
<p>Mozilla扩展，供JS实现的事件目标使用以 实现 on* 属性。另见 <a href="https://developer.mozilla.org/en-US/docs/Mozilla/WebIDL_bindings">WebIDL bindings</a> 绑定。</p>
<ul>
<li>void <strong>setEventHandler</strong>(DOMString type, EventHandler handler) {{non-standard_inline}}</li>
<li>EventHandler <strong>getEventHandler</strong>(DOMString type) {{non-standard_inline}}</li>
</ul>
<h2 id="示例">示例</h2>
<h3 id="EventTarget_的简单实现">EventTarget 的简单实现</h3>
<pre class="brush: js">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);
}
};
</pre>
<h2 id="Specification" name="Specification">规范</h2>
<table class="standard-table">
<tbody>
<tr>
<th scope="col">规范</th>
<th scope="col">状态</th>
<th scope="col">注释</th>
</tr>
<tr>
<td>{{SpecName('DOM WHATWG', '#interface-eventtarget', 'EventTarget')}}</td>
<td>{{Spec2('DOM WHATWG')}}</td>
<td>No change.</td>
</tr>
<tr>
<td>{{SpecName('DOM3 Events', 'DOM3-Events.html#interface-EventTarget', 'EventTarget')}}</td>
<td>{{Spec2('DOM3 Events')}}</td>
<td>A few parameters are now optional (<code>listener</code>), or accepts the <code>null</code> value (<code>useCapture</code>).</td>
</tr>
<tr>
<td>{{SpecName('DOM2 Events', 'events.html#Events-EventTarget', 'EventTarget')}}</td>
<td>{{Spec2('DOM2 Events')}}</td>
<td>Initial definition.</td>
</tr>
</tbody>
</table>
<h2 id="Browser_Compatibility" name="Browser_Compatibility">浏览器兼容性</h2>
<p>{{Compat("api.EventTarget")}}</p>
<h2 id="相关链接">相关链接</h2>
<ul>
<li><a href="https://developer.mozilla.org/en-US/docs/Web/Reference/Events">Event reference</a> - the events available in the platform.</li>
<li><a href="https://developer.mozilla.org/en-US/docs/Web/Guide/DOM/Events">Event developer guide</a></li>
<li>{{domxref("Event")}} interface</li>
</ul>
|
