---
title: RegExp.input ($_)
slug: Web/JavaScript/Reference/Global_Objects/RegExp/input
translation_of: Web/JavaScript/Reference/Global_Objects/RegExp/input
---
<div>{{JSRef}} {{non-standard_header}}</div>

<p><strong><code>input</code> </strong>非标准属性是正则表达式静态属性，含有正则表达式所匹配的字符串。<code>RegExp.$_</code>是这个属性的别名。</p>

<h2 id="语法">语法</h2>

<pre class="syntaxbox"><var>RegExp</var>.input
RegExp.$_
</pre>

<h2 id="描述">描述</h2>

<p><code>input</code> 属性是静态的，并不是正则表达式独立对象的属性。反之，你应始终将其使用为 <code>RegExp.input</code> 或者 <code>RegExp.$_。</code></p>

<p>当正则表达式上搜索的字符串发生改变，并且字符串匹配时，<code><strong>input</strong></code> 属性的值会修改。</p>

<h2 id="示例">示例</h2>

<h3 id="使用_input_和__">使用 <code>input</code> 和 <code>$_</code></h3>

<pre class="brush: js">var re = /hi/g;
re.test('hi there!');
RegExp.input;         // "hi there!"
re.test('foo');       // 新测试，不匹配
RegExp.$_;            // "hi there!"
re.test('hi world!'); // 新测试，匹配
RegExp.$_;            // "hi world!"
</pre>

<h2 id="规范">规范</h2>

<p>非标准。并不是任何现行规范的一部分。</p>

<h2 id="浏览器兼容性">浏览器兼容性</h2>

<div>{{CompatibilityTable}}</div>

<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</th>
  </tr>
  <tr>
   <td>Basic support</td>
   <td>{{CompatVersionUnknown}}</td>
   <td>{{CompatVersionUnknown}}</td>
   <td>{{CompatVersionUnknown}}</td>
   <td>{{CompatVersionUnknown}}</td>
   <td>{{CompatVersionUnknown}}</td>
  </tr>
 </tbody>
</table>
</div>

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

<h2 id="另见">另见</h2>

<ul>
 <li>{{non-standard_inline}} {{jsxref("RegExp.lastMatch", "RegExp.lastMatch ($&amp;)")}}</li>
 <li>{{non-standard_inline}} {{jsxref("RegExp.lastParen", "RegExp.lastParen ($+)")}}</li>
 <li>{{non-standard_inline}} {{jsxref("RegExp.leftContext", "RegExp.leftContext ($`)")}}</li>
 <li>{{non-standard_inline}} {{jsxref("RegExp.rightContext", "RegExp.rightContext ($')")}}</li>
 <li>{{non-standard_inline}} {{jsxref("RegExp.n", "RegExp.$1-$9")}}</li>
</ul>