uTools-Manuals/docs/jQuery/first-child-selector.html
2019-04-21 11:50:48 +08:00

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<h1 class="entry-title">:first-child Selector</h1>
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所属分类:<span class="category"><a href="/category/selectors/">选择器</a> &gt; <a href="/category/selectors/child-filter-selectors/">子元素过滤</a></span>
<span class="pull-right">英文文档:<a href="https://api.jquery123.com/first-child-selector/" target="_blank">:first-child Selector</a></span>
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<article class="entry selector" id="first-child1"><h2 class="section-title"><span>first-child selector</span></h2>
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<p class="desc"><strong>描述: </strong>选择所有父级元素下的第一个子元素。</p>
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<span class="version-details">添加的版本: <a href="/category/version/1.1.4/">1.1.4</a></span>jQuery( ":first-child" )</h4></li></ul>
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<p>虽然<a href="/first-selector">:first</a>只匹配一个单独的元素,但是<code>:first-child</code>选择器可以匹配多个:即为每个父级元素匹配第一个子元素。这相当于<code>:nth-child(1)</code></p>
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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">
<h4><span class="desc">给每个匹配的 div 中查找第一个 span并加上下划线及增加鼠标悬停效果。</span></h4>
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<pre><div class="container"><div class="line"><code><span class="doctype">&lt;!DOCTYPE html&gt;</span></code></div></div><div class="container"><div class="line"><code><span class="tag">&lt;<span class="title">html</span>&gt;</span></code></div></div><div class="container"><div class="line"><code><span class="tag">&lt;<span class="title">head</span>&gt;</span></code></div></div><div class="container"><div class="line"><code> <span class="tag">&lt;<span class="title">style</span>&gt;</span><span class="css"></span></code></div></div><div class="container"><div class="line"><code> <span class="tag">span</span> <span class="rules">{ <span class="rule"><span class="attribute">color</span>:<span class="value"><span class="hexcolor">#008</span>;</span></span> <span class="rule">}</span></span></code></div></div><div class="container"><div class="line"><code> <span class="tag">span</span><span class="class">.sogreen</span> <span class="rules">{ <span class="rule"><span class="attribute">color</span>:<span class="value">green;</span></span> <span class="rule"><span class="attribute">font-weight</span>:<span class="value"> bolder;</span></span> <span class="rule">}</span></span></code></div></div><div class="container"><div class="line"><code> <span class="tag">&lt;/<span class="title">style</span>&gt;</span></code></div></div><div class="container"><div class="line"><code> <span class="tag">&lt;<span class="title">script</span> <span class="attribute">src</span>=<span class="value">"https://code.jquery.com/jquery-latest.js"</span>&gt;</span><span class="javascript"></span><span class="tag">&lt;/<span class="title">script</span>&gt;</span></code></div></div><div class="container"><div class="line"><code><span class="tag">&lt;/<span class="title">head</span>&gt;</span></code></div></div><div class="container"><div class="line"><code><span class="tag">&lt;<span class="title">body</span>&gt;</span></code></div></div><div class="container"><div class="line"><code> <span class="tag">&lt;<span class="title">div</span>&gt;</span></code></div></div><div class="container"><div class="line"><code> <span class="tag">&lt;<span class="title">span</span>&gt;</span>John,<span class="tag">&lt;/<span class="title">span</span>&gt;</span></code></div></div><div class="container"><div class="line"><code> <span class="tag">&lt;<span class="title">span</span>&gt;</span>Karl,<span class="tag">&lt;/<span class="title">span</span>&gt;</span></code></div></div><div class="container"><div class="line"><code> <span class="tag">&lt;<span class="title">span</span>&gt;</span>Brandon<span class="tag">&lt;/<span class="title">span</span>&gt;</span></code></div></div><div class="container"><div class="line"><code> </code></div></div><div class="container"><div class="line"><code> <span class="tag">&lt;/<span class="title">div</span>&gt;</span></code></div></div><div class="container"><div class="line"><code> <span class="tag">&lt;<span 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class="javascript"></span></code></div></div><div class="container"><div class="line"><code>$(<span class="string">"div span:first-child"</span>)</code></div></div><div class="container"><div class="line"><code> .css(<span class="string">"text-decoration"</span>, <span class="string">"underline"</span>)</code></div></div><div class="container"><div class="line"><code> .hover(<span class="function"><span class="keyword">function</span> <span class="params">()</span> {</span></code></div></div><div class="container"><div class="line"><code> $(<span class="keyword">this</span>).addClass(<span class="string">"sogreen"</span>);</code></div></div><div class="container"><div class="line"><code> }, <span class="function"><span class="keyword">function</span> <span class="params">()</span> {</span></code></div></div><div class="container"><div class="line"><code> $(<span class="keyword">this</span>).removeClass(<span class="string">"sogreen"</span>);</code></div></div><div class="container"><div class="line"><code> });</code></div></div><div class="container"><div class="line"><code><span class="tag">&lt;/<span class="title">script</span>&gt;</span></code></div></div><div class="container"><div class="line"><code> </code></div></div><div class="container"><div class="line"><code><span class="tag">&lt;/<span class="title">body</span>&gt;</span></code></div></div><div class="container"><div class="line"><code><span class="tag">&lt;/<span class="title">html</span>&gt;</span></code></div></div></pre>
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<h4>Demo:</h4>
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