path: root/files/zh-cn/web/api/datatransfer/cleardata/index.html

---
title: DataTransfer.clearData()
slug: Web/API/DataTransfer/clearData
tags:
  - DataTransfer.clearData()
translation_of: Web/API/DataTransfer/clearData
---
<div>{{APIRef("HTML Drag and Drop API")}}</div>

<p><strong><code>DataTransfer.clearData()</code></strong> 方法删除给定类型的拖动操作的{{domxref("DataTransfer","drag data")}}。如果给定类型的数据不存在，则此方法不执行任何操作。</p>

<p class="note">如果没有参数调用此方法，或者格式为空 ，则将删除所有类型的数据。</p>

<p>此方法不会从拖动操作中删除文件，因此如果有任何文件包含在对象的{{domxref("DataTransfer.types")}}列表中，仍然可能有一个类型为“Files”的条目在拖动。 </p>

<div class="note">
<p>该方法只能在{{event("dragstart")}} 事件的处理程序中使用，因为这是拖动操作的数据存储只能写入的时间。</p>
</div>

<h2 id="句法">句法</h2>

<pre class="syntaxbox"><var>DataTransfer</var>.clearData([<em>format</em>]);
</pre>

<h3 id="参数">参数</h3>

<dl>
 <dt><code>format</code> {{optional_inline}}</dt>
 <dd>一个 {{domxref("DOMString","string")}}指定要删除的数据类型。如果此参数为空字符串或未提供，则将删除所有类型的数据。</dd>
</dl>

<h2 id="范例">范例</h2>

<p>这个例子显示了使用{{domxref("DataTransfer")}}对象的{{domxref("DataTransfer.getData()","getData()")}}, {{domxref("DataTransfer.setData()","setData()")}} 和{{domxref("DataTransfer.clearData()","clearData()")}} 和</p>

<h3 id="HTML">HTML</h3>

<pre class="brush: html">&lt;span class="tweaked" id="source" draggable="true"&gt;
  Select this element, drag it to the Drop Zone and then release the selection to move the element.
&lt;/span&gt;
&lt;span class="tweaked" id="target"&gt;Drop Zone&lt;/span&gt;
&lt;div&gt;Status: &lt;span id="status"&gt;Drag to start&lt;/span&gt;&lt;/div&gt;
&lt;div&gt;Data is: &lt;span id="data"&gt;uninitialized&lt;/span&gt;&lt;/div&gt;
</pre>

<h3 id="CSS">CSS</h3>

<pre class="brush: css">span.tweaked {
  display: inline-block;
  margin: 1em 0;
  padding: 1em 2em;
}

#source {
  color: blue;
  border: 1px solid black;
}

#target {
  border: 1px solid black;
}
</pre>

<h3 id="JavaScript">JavaScript</h3>

<pre class="brush: js">window.addEventListener('DOMContentLoaded', function () {
  // Select HTML elements
  var draggable = document.getElementById('source');
  var dropable = document.getElementById('target');
  var status = document.getElementById('status');
  var data = document.getElementById('data');
  var dropped = false;

  // Register event handlers
  draggable.addEventListener('dragstart', dragStartHandler);
  draggable.addEventListener('dragend', dragEndHandler);
  dropable.addEventListener('dragover', dragOverHandler);
  dropable.addEventListener('dragleave', dragLeaveHandler);
  dropable.addEventListener('drop', dropHandler);

  function dragStartHandler (event) {
    status.innerHTML = 'Drag in process';

    // Change target element's border to signify drag has started
    event.currentTarget.style.border = '1px dashed blue';

    // Start by clearing existing clipboards; this will affect all types since we
    // don't give a specific type.

    event.dataTransfer.clearData();

    // Set the drag's format and data (use event target's id for data)
    event.dataTransfer.setData('text/plain', event.target.id);

    data.innerHTML = event.dataTransfer.getData('text/plain');
  }

  function dragEndHandler (event) {
    if (!dropped) {
      status.innerHTML = 'Drag canceled';
    }

    data.innerHTML = event.dataTransfer.getData('text/plain') || 'empty';

    // Change border to signify drag is no longer in process
    event.currentTarget.style.border = '1px solid black';

    if (dropped) {
      // Remove all event listeners
      draggable.removeEventListener('dragstart', dragStartHandler);
      draggable.removeEventListener('dragend', dragEndHandler);
      dropable.removeEventListener('dragover', dragOverHandler);
      dropable.removeEventListener('dragleave', dragLeaveHandler);
      dropable.removeEventListener('drop', dropHandler);
    }
  }

  function dragOverHandler (event) {
    status.innerHTML = 'Drop available';

    event.preventDefault();
  }

  function dragLeaveHandler (event) {
    status.innerHTML = 'Drag in process (drop was available)';

    event.preventDefault();
  }

  function dropHandler (event) {
    dropped = true;

    status.innerHTML = 'Drop done';

    event.preventDefault();

    // Get data linked to event format « text »
    var _data = event.dataTransfer.getData('text/plain');
    var element = document.getElementById(_data);

    // Append drag source element to event's target element
    event.target.appendChild(element);

    // Change CSS styles and displayed text
    element.style.cssText = 'border: 1px solid black;display: block; color: red';
    element.innerHTML = "I'm in the Drop Zone!";
  }
})
</pre>

<p>{{EmbedLiveSample('Example', 300, 250)}}</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#dom-datatransfer-cleardata','DataTransfer.clearData()')}}</td>
   <td>{{Spec2('HTML WHATWG')}}</td>
   <td> </td>
  </tr>
  <tr>
   <td>{{SpecName('HTML5.1', 'editing.html#dom-datatransfer-cleardata','DataTransfer.clearData()')}}</td>
   <td>{{Spec2('HTML5.1')}}</td>
   <td>Initial definition</td>
  </tr>
 </tbody>
</table>

<h2 id="浏览器兼容性">浏览器兼容性</h2>

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

<div id="compat-desktop">
<table class="compat-table">
 <tbody>
  <tr>
   <th>Feature</th>
   <th>Chrome</th>
   <th>Edge</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>{{CompatVersionUnknown}}</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>Edge</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>{{CompatVersionUnknown}}</td>
   <td>{{CompatNo}}</td>
   <td>{{CompatNo}}</td>
   <td>{{CompatIE("10")}}</td>
   <td>{{CompatNo}}</td>
   <td>{{CompatNo}}</td>
  </tr>
 </tbody>
</table>
</div>

<h2 id="也可以看看">也可以看看</h2>

<p>{{page("/en-US/docs/Web/API/DataTransfer", "See also")}}</p>