mirror of
https://github.com/fofolee/uTools-Manuals.git
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92 lines
6.9 KiB
HTML
92 lines
6.9 KiB
HTML
<article class="" id="post-">
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<header class="entry-header">
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<h1 class="entry-title">.first()</h1>
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<div class="entry-meta">
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所属分类：<span class="category"><a href="/category/traversing/">遍历</a> > <a href="/category/traversing/filtering/">过滤</a></span>
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<span class="pull-right">英文文档：<a href="https://api.jquery123.com/first/" target="_blank">.first()</a></span>
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</div><!-- .entry-meta -->
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</header><!-- .entry-header -->
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<!-- .entry-header -->
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<div class="entry-content">
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<article class="entry method" id="first1"><h2 class="section-title">
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<span class="name">.first()</span><span class="returns">返回: <a href="/Types/#jQuery">jQuery</a></span>
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</h2>
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<div class="entry-wrapper">
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<p class="desc"><strong>描述: </strong>获取匹配元素集合中第一个元素。</p>
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<ul class="signatures"><li class="signature" id="first">
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<h4 class="name">
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<span class="version-details">添加的版本: <a href="/category/version/1.4/">1.4</a></span>.first()</h4>
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<ul><li><div class="null-signature">这个方法不接受任何参数。</div></li></ul>
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</li></ul>
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<div class="longdesc" id="entry-longdesc">
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<p>如果一个jQuery对象表示一个DOM元素的集合，<code>.first()</code>方法会构造一个新的jQuery对象，它包含了前一个集合的第一个元素。</p>
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<p>考虑一个页面上的一个简单的列表：</p>
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<div class="syntaxhighlighter xml nogutter">
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<table>
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<tbody>
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<tr>
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<td class="gutter">
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<div class="line n1">1</div>
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<div class="line n2">2</div>
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<div class="line n3">3</div>
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<div class="line n4">4</div>
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<div class="line n5">5</div>
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<div class="line n6">6</div>
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<div class="line n7">7</div>
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</td>
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<td class="code">
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<pre><div class="container"><div class="line"><code><span class="tag"><<span class="title">ul</span>></span></code></div></div><div class="container"><div class="line"><code> <span class="tag"><<span class="title">li</span>></span>list item 1<span class="tag"></<span class="title">li</span>></span></code></div></div><div class="container"><div class="line"><code> <span class="tag"><<span class="title">li</span>></span>list item 2<span class="tag"></<span class="title">li</span>></span></code></div></div><div class="container"><div class="line"><code> <span class="tag"><<span class="title">li</span>></span>list item 3<span class="tag"></<span class="title">li</span>></span></code></div></div><div class="container"><div class="line"><code> <span class="tag"><<span class="title">li</span>></span>list item 4<span class="tag"></<span class="title">li</span>></span></code></div></div><div class="container"><div class="line"><code> <span class="tag"><<span class="title">li</span>></span>list item 5<span class="tag"></<span class="title">li</span>></span></code></div></div><div class="container"><div class="line"><code><span class="tag"></<span class="title">ul</span>></span></code></div></div></pre>
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</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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<p>我们可以应用此方法设置列表项：</p>
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<div class="syntaxhighlighter javascript nogutter">
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<table>
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<tbody>
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<tr>
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<td class="gutter">
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<div class="line n1">1</div>
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</td>
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<td class="code">
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<pre><div class="container"><div class="line"><code>$(<span class="string">'li'</span>).first().css(<span class="string">'background-color'</span>, <span class="string">'red'</span>);</code></div></div></pre>
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</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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<p>调用的结果是第一个列表项目为红色背景。</p>
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</div>
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<section class="entry-examples" id="entry-examples"><header><h2 class="underline">例子:</h2></header><div class="entry-example" id="example-0">
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<h4><span class="desc">高亮段落中的第一个span 。</span></h4>
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<div class="syntaxhighlighter xml ">
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<table>
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<tbody>
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<tr>
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<td class="gutter">
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<div class="line n1">1</div>
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<div class="line n2">2</div>
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<div class="line n3">3</div>
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<div class="line n4">4</div>
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<div class="line n5">5</div>
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<div class="line n6">6</div>
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<div class="line n7">7</div>
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<div class="line n8">8</div>
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<div class="line n9">9</div>
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<div class="line n10">10</div>
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<div class="line n11">11</div>
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<div class="line n12">12</div>
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</td>
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<td class="code">
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<pre><div class="container"><div class="line"><code><span class="doctype"><!DOCTYPE html></span></code></div></div><div class="container"><div class="line"><code><span class="tag"><<span class="title">html</span>></span></code></div></div><div class="container"><div class="line"><code><span class="tag"><<span class="title">head</span>></span></code></div></div><div class="container"><div class="line"><code> <span class="tag"><<span class="title">style</span>></span><span class="css"><span class="class">.highlight</span><span class="rules">{<span class="rule"><span class="attribute">background-color</span>:<span class="value"> yellow}</span></span></span></span><span class="tag"></<span class="title">style</span>></span></code></div></div><div class="container"><div class="line"><code> <span class="tag"><<span class="title">script</span> <span class="attribute">src</span>=<span class="value">"https://code.jquery.com/jquery-latest.js"</span>></span><span class="javascript"></span><span class="tag"></<span class="title">script</span>></span></code></div></div><div class="container"><div class="line"><code><span class="tag"></<span class="title">head</span>></span></code></div></div><div class="container"><div class="line"><code><span class="tag"><<span class="title">body</span>></span></code></div></div><div class="container"><div class="line"><code> <span class="tag"><<span class="title">p</span>></span><span class="tag"><<span class="title">span</span>></span>Look:<span class="tag"></<span class="title">span</span>></span> <span class="tag"><<span class="title">span</span>></span>This is some text in a paragraph.<span class="tag"></<span class="title">span</span>></span> <span class="tag"><<span class="title">span</span>></span>This is a note about it.<span class="tag"></<span class="title">span</span>></span><span class="tag"></<span class="title">p</span>></span></code></div></div><div class="container"><div class="line"><code><span class="tag"><<span class="title">script</span>></span><span class="javascript">$(<span class="string">"p span"</span>).first().addClass(<span class="string">'highlight'</span>);</span><span class="tag"></<span class="title">script</span>></span></code></div></div><div class="container"><div class="line"><code> </code></div></div><div class="container"><div class="line"><code><span class="tag"></<span class="title">body</span>></span></code></div></div><div class="container"><div class="line"><code><span class="tag"></<span class="title">html</span>></span></code></div></div></pre>
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</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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<h4>Demo:</h4>
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<div class="demo code-demo"></div>
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</div></section>
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</div></article> </div>
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</article> |