uTools-Manuals/docs/javascript/Reference/Global_Objects/RegExp/exec.html

<article id="wikiArticle">
<div></div>
<p><code><strong>exec() </strong></code>方法在一个指定字符串中执行一个搜索匹配。返回一个结果数组或 <a href="Reference/Global_Objects/null" title="值 null 特指对象的值未设置。它是 JavaScript 基本类型 之一。"><code>null</code></a>。</p>
<p>如果你只是为了判断是否匹配（true或 false），可以使用 <a href="Reference/Global_Objects/RegExp/test" title="test() 方法执行一个检索，用来查看正则表达式与指定的字符串是否匹配。返回 true 或 false。"><code>RegExp.test()</code></a> 方法，或者 <a href="Reference/Global_Objects/String/search" title="search() 方法执行正则表达式和 String对象之间的一个搜索匹配。"><code>String.search()</code></a> 方法。</p>
<div><iframe class="interactive interactive-js" frameborder="0" height="250" src="https://interactive-examples.mdn.mozilla.net/pages/js/regexp-prototype-exec.html" width="100%"></iframe></div>
<p class="hidden">The source for this interactive example is stored in a GitHub repository. If you'd like to contribute to the interactive examples project, please clone <a class="external" href="https://github.com/mdn/interactive-examples" rel="noopener">https://github.com/mdn/interactive-examples</a> and send us a pull request.</p>
<h2 id="Syntax" name="Syntax">语法</h2>
<pre><code class="language-javascript"><var>regexObj</var>.exec(<var>str</var>)</code></pre>
<h3 id="Parameters" name="Parameters">参数</h3>
<dl>
<dt><code>str</code></dt>
<dd>要匹配正则表达式的字符串。</dd>
</dl>
<h3 id="Description" name="Description">返回值</h3>
<p>如果匹配成功，<code>exec</code>() 方法返回一个数组，并更新正则表达式对象的属性。返回的数组将完全匹配成功的文本作为第一项，将正则括号里匹配成功的作为数组填充到后面。</p>
<p>如果匹配失败，exec() 方法返回 <a href="Reference/Global_Objects/null" title="值 null 特指对象的值未设置。它是 JavaScript 基本类型 之一。"><code>null</code></a>。</p>
<h2 id="描述">描述</h2>
<p>考虑以下示例：</p>
<pre><code  class="language-javascript">// Match "quick brown" followed by "jumps", ignoring characters in between
// Remember "brown" and "jumps"
// Ignore case
var re = /quick\s(brown).+?(jumps)/ig;
var result = re.exec('The Quick Brown Fox Jumps Over The Lazy Dog');
</code></pre>
<p>下表列出这个脚本的返回值：</p>
<table class="fullwidth-table">
<tbody>
<tr>
<td class="header">对象</td>
<td class="header">属性/索引</td>
<td class="header">描述</td>
<td class="header">例子</td>
</tr>
<tr>
<td rowspan="4"><code>result</code></td>
<td><code>[0]</code></td>
<td>匹配的全部字符串</td>
<td><code>Quick Brown Fox Jumps</code></td>
</tr>
<tr>
<td><code>[1], ...[<em>n</em> ]</code></td>
<td>括号中的分组捕获</td>
<td><code>[1] = Brown<br/>
    [2] = Jumps</code></td>
</tr>
<tr>
<td><code>index</code></td>
<td>匹配到的字符位于原始字符串的基于0的索引值</td>
<td><code>4</code></td>
</tr>
<tr>
<td><code>input</code></td>
<td>原始字符串</td>
<td><code>The Quick Brown Fox Jumps Over The Lazy Dog</code></td>
</tr>
<tr>
<td rowspan="5"><code>re</code></td>
<td><code>lastIndex</code></td>
<td>下一次匹配开始的位置</td>
<td><code>25</code></td>
</tr>
<tr>
<td><code>ignoreCase</code></td>
<td>是否使用了 "<code>i</code>" 标记使正则匹配忽略大小写</td>
<td><code>true</code></td>
</tr>
<tr>
<td><code>global</code></td>
<td>是否使用了 "<code>g</code>" 标记来进行全局的匹配.</td>
<td><code>true</code></td>
</tr>
<tr>
<td><code>multiline</code></td>
<td>
<p>是否使用了 "<code>m</code>" 标记使正则工作在多行模式（也就是，^ 和 $ 可以匹配字符串中每一行的开始和结束（行是由 \n 或 \r 分割的），而不只是整个输入字符串的最开始和最末尾处。）</p>
</td>
<td><code>false</code></td>
</tr>
<tr>
<td><code>source</code></td>
<td>正则匹配的字符串</td>
<td><code>quick\s(brown).+?(jumps)</code></td>
</tr>
</tbody>
</table>
<h2 id="示例">示例</h2>
<h3 id="查找所有匹配">查找所有匹配</h3>
<p>当正则表达式使用 "<code>g</code>" 标志时，可以多次执行 <code>exec</code> 方法来查找同一个字符串中的成功匹配。当你这样做时，查找将从正则表达式的 <a href="Reference/Global_Objects/RegExp/lastIndex" title="lastIndex 是正则表达式的一个可读可写的整型属性，用来指定下一次匹配的起始索引。"><code>lastIndex</code></a> 属性指定的位置开始。（<a href="Reference/Global_Objects/RegExp/test" title="test() 方法执行一个检索，用来查看正则表达式与指定的字符串是否匹配。返回 true 或 false。"><code>test()</code></a> 也会更新 <code>lastIndex</code> 属性）。例如，你使用下面的脚本：</p>
<pre><code  class="language-javascript">var myRe = /ab*/g;
var str = 'abbcdefabh';
var myArray;
while ((myArray = myRe.exec(str)) !== null) {
  var msg = 'Found ' + myArray[0] + '. ';
  msg += 'Next match starts at ' + myRe.lastIndex;
  console.log(msg);
}
</code></pre>
<p>脚本运行结果如下：</p>
<pre>Found abb. Next match starts at 3
Found ab. Next match starts at 9
</code></pre>
<p>注意：不要把正则表达式字面量（或者<a href="Reference/RegExp" title="此页面仍未被本地化, 期待您的翻译!"><code>RegExp</code></a>构造器）放在 <code>while</code> 条件表达式里。由于每次迭代时 <a href="Reference/Global_Objects/RegExp/lastIndex" title="lastIndex 是正则表达式的一个可读可写的整型属性，用来指定下一次匹配的起始索引。"><code>lastIndex</code></a>的属性都被重置，如果匹配，将会造成一个死循环。并且要确保使用了'g'标记来进行全局的匹配，否则同样会造成死循环。</p>
<h3 id="结合_RegExp_字面量使用_exec()">结合 <code>RegExp</code> 字面量使用 <code>exec()</code></h3>
<p>你也可以直接使用 <code>exec()</code> 而不是创建一个 <a href="Reference/RegExp" title="此页面仍未被本地化, 期待您的翻译!"><code>RegExp</code></a>  对象：</p>
<pre><code  class="language-javascript">var matches = /(hello \S+)/.exec('This is a hello world!');
console.log(matches[1]);
</code></pre>
<p>运行上面的代码，控制台会输出"hello world!" 字符串。</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><a class="external" href="https://www.ecma-international.org/publications/files/ECMA-ST-ARCH/ECMA-262,%203rd%20edition,%20December%201999.pdf" hreflang="en" lang="en" rel="noopener" title="ECMAScript 3rd Edition (ECMA-262)">ECMAScript 3rd Edition (ECMA-262)</a></td>
<td><span class="spec-Standard">Standard</span></td>
<td>Initial definition. Implemented in JavaScript 1.2.</td>
</tr>
<tr>
<td><a class="external" href="https://www.ecma-international.org/ecma-262/5.1/#sec-15.10.6.21" hreflang="en" lang="en" rel="noopener">ECMAScript 5.1 (ECMA-262)<br/><small lang="zh-CN">RegExp.exec</small></a></td>
<td><span class="spec-Standard">Standard</span></td>
<td> </td>
</tr>
<tr>
<td><a class="external" href="https://www.ecma-international.org/ecma-262/6.0/#sec-regexp.prototype.exec" hreflang="en" lang="en" rel="noopener">ECMAScript 2015 (6th Edition, ECMA-262)<br/><small lang="zh-CN">RegExp.exec</small></a></td>
<td><span class="spec-Standard">Standard</span></td>
<td> </td>
</tr>
<tr>
<td><a class="external" href="https://tc39.github.io/ecma262/#sec-regexp.prototype.exec" hreflang="en" lang="en" rel="noopener">ECMAScript Latest Draft (ECMA-262)<br/><small lang="zh-CN">RegExp.exec</small></a></td>
<td><span class="spec-Draft">Draft</span></td>
<td> </td>
</tr>
</tbody>
</table>
<h2 id="浏览器兼容性">浏览器兼容性</h2>
<div>
<div class="hidden">The compatibility table on this page is generated from structured data. If you'd like to contribute to the data, please check out <a class="external" href="https://github.com/mdn/browser-compat-data" rel="noopener">https://github.com/mdn/browser-compat-data</a> and send us a pull request.</div>
<p></p><div class="bc-data"><a class="bc-github-link external" href="https://github.com/mdn/browser-compat-data" rel="noopener">Update compatibility data on GitHub</a><table class="bc-table bc-table-js"><thead><tr class="bc-platforms"><td></td><th class="bc-platform-desktop" colspan="6"><span>Desktop</span></th><th class="bc-platform-mobile" colspan="7"><span>Mobile</span></th><th class="bc-platform-server" colspan="1"><span>Server</span></th></tr><tr class="bc-browsers"><td></td><th class="bc-browser-chrome"><span class="bc-head-txt-label bc-head-icon-chrome">Chrome</span></th><th class="bc-browser-edge"><span class="bc-head-txt-label bc-head-icon-edge">Edge</span></th><th class="bc-browser-firefox"><span class="bc-head-txt-label bc-head-icon-firefox">Firefox</span></th><th class="bc-browser-ie"><span class="bc-head-txt-label bc-head-icon-ie">Internet Explorer</span></th><th class="bc-browser-opera"><span class="bc-head-txt-label bc-head-icon-opera">Opera</span></th><th class="bc-browser-safari"><span class="bc-head-txt-label bc-head-icon-safari">Safari</span></th><th class="bc-browser-webview_android"><span class="bc-head-txt-label bc-head-icon-webview_android">Android webview</span></th><th class="bc-browser-chrome_android"><span class="bc-head-txt-label bc-head-icon-chrome_android">Chrome for Android</span></th><th class="bc-browser-edge_mobile"><span class="bc-head-txt-label bc-head-icon-edge_mobile">Edge Mobile</span></th><th class="bc-browser-firefox_android"><span class="bc-head-txt-label bc-head-icon-firefox_android">Firefox for Android</span></th><th class="bc-browser-opera_android"><span class="bc-head-txt-label bc-head-icon-opera_android">Opera for Android</span></th><th class="bc-browser-safari_ios"><span class="bc-head-txt-label bc-head-icon-safari_ios">Safari on iOS</span></th><th class="bc-browser-samsunginternet_android"><span class="bc-head-txt-label bc-head-icon-samsunginternet_android">Samsung Internet</span></th><th class="bc-browser-nodejs"><span class="bc-head-txt-label bc-head-icon-nodejs">Node.js</span></th></tr></thead><tbody><tr><th scope="row"><code>exec</code></th><td class="bc-supports-yes bc-browser-chrome"><span class="bc-browser-name">Chrome</span><abbr class="bc-level-yes only-icon" title="Full support">
<span>Full support</span>
</abbr>
              Yes</td><td class="bc-supports-yes bc-browser-edge"><span class="bc-browser-name">Edge</span><abbr class="bc-level-yes only-icon" title="Full support">
<span>Full support</span>
</abbr>
              12</td><td class="bc-supports-yes bc-browser-firefox"><span class="bc-browser-name">Firefox</span><abbr class="bc-level-yes only-icon" title="Full support">
<span>Full support</span>
</abbr>
              1</td><td class="bc-supports-yes bc-browser-ie"><span class="bc-browser-name">IE</span><abbr class="bc-level-yes only-icon" title="Full support">
<span>Full support</span>
</abbr>
              Yes</td><td class="bc-supports-yes bc-browser-opera"><span class="bc-browser-name">Opera</span><abbr class="bc-level-yes only-icon" title="Full support">
<span>Full support</span>
</abbr>
              Yes</td><td class="bc-supports-yes bc-browser-safari"><span class="bc-browser-name">Safari</span><abbr class="bc-level-yes only-icon" title="Full support">
<span>Full support</span>
</abbr>
              Yes</td><td class="bc-supports-yes bc-browser-webview_android"><span class="bc-browser-name">WebView Android</span><abbr class="bc-level-yes only-icon" title="Full support">
<span>Full support</span>
</abbr>
              Yes</td><td class="bc-supports-yes bc-browser-chrome_android"><span class="bc-browser-name">Chrome Android</span><abbr class="bc-level-yes only-icon" title="Full support">
<span>Full support</span>
</abbr>
              Yes</td><td class="bc-supports-yes bc-browser-edge_mobile"><span class="bc-browser-name">Edge Mobile</span><abbr class="bc-level-yes only-icon" title="Full support">
<span>Full support</span>
</abbr>
              Yes</td><td class="bc-supports-yes bc-browser-firefox_android"><span class="bc-browser-name">Firefox Android</span><abbr class="bc-level-yes only-icon" title="Full support">
<span>Full support</span>
</abbr>
              4</td><td class="bc-supports-yes bc-browser-opera_android"><span class="bc-browser-name">Opera Android</span><abbr class="bc-level-yes only-icon" title="Full support">
<span>Full support</span>
</abbr>
              Yes</td><td class="bc-supports-yes bc-browser-safari_ios"><span class="bc-browser-name">Safari iOS</span><abbr class="bc-level-yes only-icon" title="Full support">
<span>Full support</span>
</abbr>
              Yes</td><td class="bc-supports-yes bc-browser-samsunginternet_android"><span class="bc-browser-name">Samsung Internet Android</span><abbr class="bc-level-yes only-icon" title="Full support">
<span>Full support</span>
</abbr>
              Yes</td><td class="bc-supports-yes bc-browser-nodejs"><span class="bc-browser-name">nodejs</span><abbr class="bc-level-yes only-icon" title="Full support">
<span>Full support</span>
</abbr>
              Yes</td></tr></tbody></table><section class="bc-legend" id="sect1"><h3 class="offscreen" id="Legend">Legend</h3><dl><dt><span class="bc-supports-yes bc-supports">
<abbr class="bc-level bc-level-yes only-icon" title="Full support">
<span>Full support</span>
                  
                </abbr></span></dt><dd>Full support</dd></dl></section></div><p></p>
</div>
<h2 id="相关链接">相关链接</h2>
<ul>
<li><a href="/en-US/docs/Web/JavaScript/Guide/Regular_Expressions">Regular Expressions</a> chapter in the <a href="/en-US/docs/Web/JavaScript/Guide">JavaScript Guide</a></li>
<li><a href="Reference/RegExp" title="此页面仍未被本地化, 期待您的翻译!"><code>RegExp</code></a></li>
</ul>
</article>