---
title: dragover
slug: Web/API/Document/dragover_event
tags:
  - DOM
  - Event
  - drag and drop
  - 事件
  - 参考
  - 拖拽
translation_of: Web/API/Document/dragover_event
---
<div>{{APIRef}}</div>

<p>当元素或者选择的文本被拖拽到一个有效的放置目标上时，触发 <code>dragover </code>事件(每几百毫秒触发一次)。</p>

<p>这个事件在可被放置元素的节点上触发。</p>

<h2 id="基本信息">基本信息</h2>

<table class="properties">
 <tbody>
  <tr>
   <td>是否冒泡</td>
   <td>是</td>
  </tr>
  <tr>
   <td>是否可以取消</td>
   <td>是</td>
  </tr>
  <tr>
   <td>目标对象</td>
   <td>{{domxref("Document")}}, {{domxref("Element")}}</td>
  </tr>
  <tr>
   <td>接口</td>
   <td>{{domxref("DragEvent")}}</td>
  </tr>
  <tr>
   <td>默认行为</td>
   <td>重置当前的拖拽动作为"none"</td>
  </tr>
 </tbody>
</table>

<h2 id="属性">属性</h2>

<table class="standard-table">
 <thead>
  <tr>
   <th scope="col">Property</th>
   <th scope="col">Type</th>
   <th scope="col">Description</th>
  </tr>
 </thead>
 <tbody>
  <tr>
   <td><code>target</code> {{readonlyInline}}</td>
   <td><a href="/en-US/docs/Web/API/EventTarget" title="EventTarget is an interface implemented by objects that can receive events and may have listeners for them."><code>EventTarget</code></a></td>
   <td>The element that was underneath the element being dragged.</td>
  </tr>
  <tr>
   <td><code>type</code> {{readonlyInline}}</td>
   <td><a href="/en-US/docs/Web/API/DOMString" title="DOMString is a UTF-16 String. As JavaScript already uses such strings, DOMString is mapped directly to a String."><code>DOMString</code></a></td>
   <td>The type of event.</td>
  </tr>
  <tr>
   <td><code>bubbles</code> {{readonlyInline}}</td>
   <td><a href="/en-US/docs/Web/API/Boolean" title="The Boolean object is an object wrapper for a boolean value."><code>Boolean</code></a></td>
   <td>Whether the event normally bubbles or not</td>
  </tr>
  <tr>
   <td><code>cancelable</code> {{readonlyInline}}</td>
   <td><a href="/en-US/docs/Web/API/Boolean" title="The Boolean object is an object wrapper for a boolean value."><code>Boolean</code></a></td>
   <td>Whether the event is cancellable or not?</td>
  </tr>
  <tr>
   <td><code>view</code> {{readonlyInline}}</td>
   <td><a class="new" href="/en-US/docs/Web/API/WindowProxy" rel="nofollow" title="The documentation about this has not yet been written; please consider contributing!"><code>WindowProxy</code></a></td>
   <td><a href="/en-US/docs/Web/API/Document/defaultView" title="In browsers, document.defaultView returns the window object associated with a document, or null if none is available."><code>document.defaultView</code></a> (<code>window</code> of the document)</td>
  </tr>
  <tr>
   <td><code>detail</code> {{readonlyInline}}</td>
   <td><code>long</code> (<code>float</code>)</td>
   <td>0.</td>
  </tr>
  <tr>
   <td><code>dataTransfer</code></td>
   <td>DataTransfer</td>
   <td>The data that underlies a drag-and-drop operation, known as the <a href="/en-US/docs/Web/API/DataTransfer">drag data store</a>. Protected mode.</td>
  </tr>
  <tr>
   <td><code>currentTarget</code> {{readonlyInline}}</td>
   <td>EventTarget</td>
   <td>The node that had the event listener attached.</td>
  </tr>
  <tr>
   <td><code>relatedTarget</code> {{readonlyInline}}</td>
   <td>EventTarget</td>
   <td>For <code>mouseover</code>, <code>mouseout</code>, <code>mouseenter</code> and <code>mouseleave</code> events: the target of the complementary event (the <code>mouseleave</code> target in the case of a <code>mouseenter</code> event). <code>null</code> otherwise.</td>
  </tr>
  <tr>
   <td><code>screenX</code> {{readonlyInline}}</td>
   <td>long</td>
   <td>The X coordinate of the mouse pointer in global (screen) coordinates.</td>
  </tr>
  <tr>
   <td><code>screenY</code> {{readonlyInline}}</td>
   <td>long</td>
   <td>The Y coordinate of the mouse pointer in global (screen) coordinates.</td>
  </tr>
  <tr>
   <td><code>clientX</code> {{readonlyInline}}</td>
   <td>long</td>
   <td>The X coordinate of the mouse pointer in local (DOM content) coordinates.</td>
  </tr>
  <tr>
   <td><code>clientY</code> {{readonlyInline}}</td>
   <td>long</td>
   <td>The Y coordinate of the mouse pointer in local (DOM content) coordinates.</td>
  </tr>
  <tr>
   <td><code>button</code> {{readonlyInline}}</td>
   <td>unsigned short</td>
   <td>The button number that was pressed when the mouse event was fired: Left button=0, middle button=1 (if present), right button=2. For mice configured for left handed use in which the button actions are reversed the values are instead read from right to left.</td>
  </tr>
  <tr>
   <td><code>buttons</code> {{readonlyInline}}</td>
   <td>unsigned short</td>
   <td>The buttons being pressed when the mouse event was fired: Left button=1, Right button=2, Middle (wheel) button=4, 4th button (typically, "Browser Back" button)=8, 5th button (typically, "Browser Forward" button)=16. If two or more buttons are pressed, returns the logical sum of the values. E.g., if Left button and Right button are pressed, returns 3 (=1 | 2). <a href="/en-US/docs/Web/API/MouseEvent">More info</a>.</td>
  </tr>
  <tr>
   <td><code>mozPressure</code> {{readonlyInline}}</td>
   <td>float</td>
   <td>The amount of pressure applied to a touch or tabdevice when generating the event; this value ranges between 0.0 (minimum pressure) and 1.0 (maximum pressure).</td>
  </tr>
  <tr>
   <td><code>ctrlKey</code> {{readonlyInline}}</td>
   <td>boolean</td>
   <td><code>true</code> if the control key was down when the event was fired. <code>false</code> otherwise.</td>
  </tr>
  <tr>
   <td><code>shiftKey</code> {{readonlyInline}}</td>
   <td>boolean</td>
   <td><code>true</code> if the shift key was down when the event was fired. <code>false</code> otherwise.</td>
  </tr>
  <tr>
   <td><code>altKey</code> {{readonlyInline}}</td>
   <td>boolean</td>
   <td><code>true</code> if the alt key was down when the event was fired. <code>false</code> otherwise.</td>
  </tr>
  <tr>
   <td><code>metaKey</code> {{readonlyInline}}</td>
   <td>boolean</td>
   <td><code>true</code> if the meta key was down when the event was fired. <code>false</code> otherwise.</td>
  </tr>
 </tbody>
</table>

<h2 id="示例：dropzone">示例：dropzone</h2>

<p>{{page('/zh-CN/docs/Web/Events/dragstart', '示例：dropzone')}}</p>

<h2 id="规范">规范</h2>

<table class="standard-table">
 <tbody>
  <tr>
   <th scope="col">Specification</th>
   <th scope="col">Status</th>
   <th scope="col">Comment</th>
  </tr>
  <tr>
   <td>{{SpecName("HTML WHATWG", "interaction.html#dndevents", "dragover")}}</td>
   <td>{{Spec2("HTML WHATWG")}}</td>
   <td> </td>
  </tr>
  <tr>
   <td>{{SpecName("HTML5.1", "editing.html#dndevents", "dragover")}}</td>
   <td>{{Spec2("HTML5.1")}}</td>
   <td>Initial definition</td>
  </tr>
 </tbody>
</table>

<h2 id="浏览器支持">浏览器支持</h2>

<p>{{CompatibilityTable}}</p>

<div id="compat-desktop">
<table class="compat-table">
 <tbody>
  <tr>
   <th>Feature</th>
   <th>Chrome</th>
   <th>Firefox (Gecko)</th>
   <th>Internet Explorer</th>
   <th>Opera</th>
   <th>Safari (WebKit)</th>
  </tr>
  <tr>
   <td>Basic support</td>
   <td>4</td>
   <td>{{CompatGeckoDesktop("1.9.1")}}</td>
   <td>10</td>
   <td>12</td>
   <td>3.1</td>
  </tr>
 </tbody>
</table>
</div>

<div id="compat-mobile">
<table class="compat-table">
 <tbody>
  <tr>
   <th>Feature</th>
   <th>Android</th>
   <th>Android Webview</th>
   <th>Chrome for Android</th>
   <th>Firefox Mobile (Gecko)</th>
   <th>Firefox OS</th>
   <th>IE Mobile</th>
   <th>Opera Mobile</th>
   <th>Safari Mobile</th>
  </tr>
  <tr>
   <td>Basic support</td>
   <td>{{CompatNo}}</td>
   <td>{{CompatNo}}</td>
   <td>{{CompatNo}}</td>
   <td>{{CompatNo}}</td>
   <td>{{CompatNo}}</td>
   <td>{{CompatIE("10")}}</td>
   <td>{{CompatNo}}</td>
   <td>{{CompatNo}}</td>
  </tr>
 </tbody>
</table>
</div>

<h2 id="相关">相关</h2>

<ul>
 <li>{{event("drag")}}</li>
 <li>{{event("dragstart")}}</li>
 <li>{{event("dragend")}}</li>
 <li>{{event("dragover")}}</li>
 <li>{{event("dragenter")}}</li>
 <li>{{event("dragleave")}}</li>
 <li>{{event("dragexit")}}</li>
 <li>{{event("drop")}}</li>
</ul>