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179 lines
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179 lines
8.7 KiB
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<article id="wikiArticle">
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<div></div>
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<p><strong><code>sticky</code></strong> 属性反映了搜索是否具有粘性（ 仅从正则表达式的 <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> 属性表示的索引处搜索 ）。<code>sticky</code> 是正则表达式对象的只读属性。</p>
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<div><table class="standard-table">
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<thead>
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<tr>
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<th class="header" colspan="2"><code>RegExp.prototype.sticky</code> 属性的属性特性：</th>
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</tr>
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</thead>
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<tbody>
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<tr>
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<td>writable</td>
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<td>false</td>
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</tr>
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<tr>
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<td>enumerable</td>
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<td>false</td>
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</tr>
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<tr>
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<td>configurable</td>
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<td>true</td>
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</tr>
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</tbody>
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</table></div>
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<h2 id="描述">描述</h2>
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<p><code>sticky</code> 的值是 <a href="Reference/Boolean" title="此页面仍未被本地化, 期待您的翻译!"><code>Boolean</code></a> ，并在“<code>y</code>”标志使用时为真; 否则为假。"<code>y</code>" 标志指示，仅从正则表达式的 <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> 属性表示的索引处为目标字符串匹配（并且不会尝试从后续索引匹配）。</p>
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<p>你不能直接更改这个属性，它是只读的。</p>
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<h2 id="例子">例子</h2>
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<h3 id="使用带_sticky_标志的正则表达式">使用带 sticky 标志的正则表达式</h3>
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<pre><code class="language-javascript">var str = '#foo#';
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var regex = /foo/y;
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regex.lastIndex = 1;
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regex.test(str); // true （译注：此例仅当 lastIndex = 1 时匹配成功，这就是 sticky 的作用）
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regex.lastIndex = 5;
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regex.test(str); // false （lastIndex 被 sticky 标志考虑到，从而导致匹配失败）
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regex.lastIndex; // 0 （匹配失败后重置）
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</code></pre>
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<h3 id="锚定的_sticky_标志">锚定的 sticky 标志</h3>
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<p>火狐的 SpiderMonkey 引擎的几个版本有一个 <a class="external" href="https://bugzilla.mozilla.org/show_bug.cgi?id=773687" rel="noopener">bug</a>，处理 <code>^</code> 断言和 sticky 标志时，会允许使用了 sticky 标志的表达式从 <code>^</code> 断言开始匹配，这是不应该的。这个 bug 是在 Firefox 3.6 之后的某个版本引入的（which had the sticky flag but not the bug）并于2015年修复。 可能正因为这个 bug， ES2015 规范 <a class="external" href="http://www.ecma-international.org/ecma-262/7.0/index.html#sec-assertion" rel="noopener">特别指出</a>：</p>
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<blockquote>
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<p>当使用带有y标识的匹配模式时，^断言总是会匹配输入的开始位置或者（如果是多行模式）每一行的开始位置。</p>
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</blockquote>
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<p>正确行为的示例：</p>
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<pre><code class="language-javascript">var regex = /^foo/y;
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regex.lastIndex = 2;
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regex.test("..foo"); // false - 索引2不是字符串的开始
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var regex2 = /^foo/my;
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regex2.lastIndex = 2;
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regex2.test("..foo"); // false - 索引2不是字符串或行的开始
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regex2.lastIndex = 2;
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regex2.test(".\nfoo"); // true - 索引2是行的开始
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</code></pre>
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<h2 id="规范">规范</h2>
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<table class="standard-table">
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<tbody>
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<tr>
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<th scope="col">Specification</th>
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<th scope="col">Status</th>
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<th scope="col">Comment</th>
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</tr>
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<tr>
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<td><a class="external" href="https://www.ecma-international.org/ecma-262/6.0/#sec-get-regexp.prototype.sticky" hreflang="en" lang="en" rel="noopener">ECMAScript 2015 (6th Edition, ECMA-262)<br/><small lang="zh-CN">RegExp.prototype.sticky</small></a></td>
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<td><span class="spec-Standard">Standard</span></td>
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<td>Initial definition.</td>
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</tr>
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<tr>
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<td><a class="external" href="https://tc39.github.io/ecma262/#sec-get-regexp.prototype.sticky" hreflang="en" lang="en" rel="noopener">ECMAScript Latest Draft (ECMA-262)<br/><small lang="zh-CN">RegExp.prototype.sticky</small></a></td>
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<td><span class="spec-Draft">Draft</span></td>
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<td> </td>
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</tr>
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</tbody>
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</table>
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<h2 id="浏览器兼容性">浏览器兼容性</h2>
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<div><div class="blockIndicator warning"><strong><a class="external" href="https://github.com/mdn/browser-compat-data" rel="noopener">We're converting our compatibility data into a machine-readable JSON format</a></strong>.
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This compatibility table still uses the old format,
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because we haven't yet converted the data it contains.
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<strong><a class="new" href="/zh-CN/docs/MDN/Contribute/Structures/Compatibility_tables" rel="nofollow">Find out how you can help!</a></strong></div>
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<div class="htab">
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<a id="AutoCompatibilityTable" name="AutoCompatibilityTable"></a>
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<ul>
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<li class="selected"><a>Desktop</a></li>
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<li><a>Mobile</a></li>
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</ul>
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</div></div>
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<div id="compat-desktop">
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<table class="compat-table">
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<tbody>
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<tr>
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<th>Feature</th>
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<th>Chrome</th>
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<th>Edge</th>
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<th>Firefox (Gecko)</th>
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<th>Internet Explorer</th>
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<th>Opera</th>
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<th>Safari</th>
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</tr>
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<tr>
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<td>Basic support</td>
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<td><span style="color: #f00;">未实现</span></td>
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<td><span style="color: #888;" title="Please update this with the earliest version of support.">(Yes)</span></td>
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<td><a href="/en-US/Firefox/Releases/3" title="Released on 2008-06-17.">3.0</a> (1.9)</td>
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<td><span style="color: #f00;">未实现</span></td>
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<td><span style="color: #f00;">未实现</span></td>
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<td><span style="color: #f00;">未实现</span></td>
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</tr>
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<tr>
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<td>Prototype accessor property</td>
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<td><span style="color: #f00;">未实现</span></td>
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<td><span style="color: #888;" title="Please update this with the earliest version of support.">(Yes)</span></td>
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<td><a href="/en-US/Firefox/Releases/38" title="Released on 2015-05-19.">38</a> (38)</td>
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<td><span style="color: #f00;">未实现</span></td>
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<td><span style="color: #f00;">未实现</span></td>
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<td><span style="color: #f00;">未实现</span></td>
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</tr>
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<tr>
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<td>Anchored sticky(y) flag behavior per ES2015</td>
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<td><span style="color: #f00;">未实现</span></td>
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<td><span style="color: #888;" title="Please update this with the earliest version of support.">(Yes)</span></td>
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<td><a href="/en-US/Firefox/Releases/44" title="Released on 2016-01-26.">44</a> (44)</td>
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<td><span style="color: #f00;">未实现</span></td>
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<td><span style="color: #f00;">未实现</span></td>
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<td><span style="color: #f00;">未实现</span></td>
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</tr>
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</tbody>
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</table>
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</div>
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<div id="compat-mobile">
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<table class="compat-table">
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<tbody>
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<tr>
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<th>Feature</th>
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<th>Android</th>
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<th>Chrome for Android</th>
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<th>Firefox Mobile (Gecko)</th>
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<th>IE Mobile</th>
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<th>Opera Mobile</th>
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<th>Safari Mobile</th>
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</tr>
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<tr>
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<td>Basic support</td>
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<td><span style="color: #f00;">未实现</span></td>
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<td><span style="color: #f00;">未实现</span></td>
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<td>1.0 (1.9)</td>
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<td><span style="color: #f00;">未实现</span></td>
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<td><span style="color: #f00;">未实现</span></td>
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<td><span style="color: #f00;">未实现</span></td>
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</tr>
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<tr>
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<td>Prototype accessor property</td>
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<td><span style="color: #f00;">未实现</span></td>
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<td><span style="color: #f00;">未实现</span></td>
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<td>38.0 (38)</td>
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<td><span style="color: #f00;">未实现</span></td>
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<td><span style="color: #f00;">未实现</span></td>
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<td><span style="color: #f00;">未实现</span></td>
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</tr>
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<tr>
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<td>Anchored sticky(y) flag behavior per ES2015</td>
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<td><span style="color: #f00;">未实现</span></td>
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<td><span style="color: #f00;">未实现</span></td>
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<td>44.0 (44)</td>
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<td><span style="color: #f00;">未实现</span></td>
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<td><span style="color: #f00;">未实现</span></td>
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<td><span style="color: #f00;">未实现</span></td>
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</tr>
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</tbody>
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</table>
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</div>
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<h2 id="相关链接">相关链接</h2>
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<ul>
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<li><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>RegExp.lastIndex</code></a></li>
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<li><a href="Reference/Global_Objects/RegExp/global" title='global 属性表明正则表达式是否使用了 "g" 标志。global 是一个正则表达式实例的只读属性。'><code>RegExp.prototype.global</code></a></li>
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<li><a href="Reference/Global_Objects/RegExp/ignoreCase" title='ignoreCase 属性表明正则表达式是否使用了 "i" 标志。ignoreCase 是正则表达式实例的只读属性。'><code>RegExp.prototype.ignoreCase</code></a></li>
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<li><a href="Reference/Global_Objects/RegExp/multiline" title='multiline 属性表明正则表达式是否使用了 "m" 标志。multiline 是正则表达式实例的一个只读属性。'><code>RegExp.prototype.multiline</code></a></li>
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<li><a href="Reference/Global_Objects/RegExp/source" title="source 属性返回一个值为当前正则表达式对象的模式文本的字符串，该字符串不会包含正则字面量两边的斜杠以及任何的标志字符。"><code>RegExp.prototype.source</code></a></li>
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</ul>
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</article> |