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268 lines
19 KiB
HTML
268 lines
19 KiB
HTML
<article class="" id="post-">
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<header class="entry-header">
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<h1 class="entry-title">.slice()</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/slice/" target="_blank">.slice()</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="slice1"><h2 class="section-title">
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<span class="name">.slice( start [, end ] )</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>根据指定的下标范围，过滤匹配的元素集合，并生成一个新的 jQuery 对象。</p>
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<ul class="signatures"><li class="signature" id="slice-start-end">
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<h4 class="name">
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<span class="version-details">添加的版本: <a href="/category/version/1.1.4/">1.1.4</a></span>.slice( start [, end ] )</h4>
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<ul>
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<li>
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<div><strong>start</strong></div>
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<div>类型: <a href="/Types/#Integer">Integer</a>
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</div>
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<div>一个整数，从 0 开始计数的下标。代表将要被选择的元素的起始下标。如果指定的下标是一个负数，那么代表从末尾开始计数。</div>
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</li>
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<li>
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<div><strong>end</strong></div>
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<div>类型: <a href="/Types/#Integer">Integer</a>
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</div>
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<div>一个整数，从 0 开始计数的下标。代表将要被选择的元素的结束下标。如果指定的下标是一个负数，那么代表从末尾开始计数。如果忽略此参数，则选择的范围是从 start 开始，一直到最后。</div>
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</li>
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</ul>
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</li></ul>
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<div class="longdesc" id="entry-longdesc">
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<p>如果提供的jQuery代表了一组DOM元素，<code>.slice()</code>方法从匹配元素的子集中构造一个新的jQuery对象。所提供的<code>start</code>索引标识的设置一个集合中的元素的位置;如果<code>end</code>被省略，这个元素之后的所有元素将包含在结果中。</p>
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<p>考虑一个页上有一个简单的列表：</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到列表集合：</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>$(<span class="string">'li'</span>).slice(<span class="number">2</span>).css(<span class="string">'background-color'</span>, <span class="string">'red'</span>);</code></div></div></pre>
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</td>
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</tr>
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</tbody>
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</table>
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</div>
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<p>上述代码的执行结果是，第 3，4，5 项列表项的背景色变成了红色。注意，索引是从 0 开始计数的，并且代表的是 jQuery 对象中的元素位置，而不是在 DOM 树中的位置。</p>
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<p>end 参数允许我们进一步限制所选择的元素。例如：</p>
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<div class="syntaxhighlighter javascript nogutter">
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<table>
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<tbody>
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<tr>
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<td class="gutter">
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<div class="line n1">1</div>
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</td>
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<td class="code">
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<pre><div class="container"><div class="line"><code>$(<span class="string">'li'</span>).slice(<span class="number">2</span>, <span class="number">4</span>).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>上述代码的执行结果是，第 3，4，5 项列表项的背景色变成了红色。注意，索引是从 0 开始计数的，并且代表的是 jQuery 对象中的元素位置，而不是在 DOM 树中的位置。</p>
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<h4>Negative Indices（负指数）</h4>
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<p>jQuery的<code>.slice()</code>方法是仿照的JavaScript 数组的.slice()方法。其中的一个功能就是允许传入负的 <code>start</code> 和 <code>end</code> 参数。如果传递的是负数，那么下标位置是从结尾开始的，而不是从起始位置开始。例如：</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>).slice(-<span class="number">2</span>, -<span class="number">1</span>).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>这一次只有项4是变成了红色，因为它是唯一满足条件的列表项，即被选中的元素是从倒数第二个元素(<code>-2</code>)开始到最后一个元素(<code>-1</code> )（不含此元素）之间的元素。
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</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>Example: <span class="desc">将随机选中的范围内的 div 变成黄色。</span>
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</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 n13">13</div>
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<div class="line n14">14</div>
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<div class="line n15">15</div>
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<div class="line n16">16</div>
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<div class="line n17">17</div>
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<div class="line n19">19</div>
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<div class="line n20">20</div>
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<div class="line n21">21</div>
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<div class="line n22">22</div>
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<div class="line n23">23</div>
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<div class="line n24">24</div>
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<div class="line n25">25</div>
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<div class="line n26">26</div>
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<div class="line n27">27</div>
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<div class="line n28">28</div>
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<div class="line n29">29</div>
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<div class="line n30">30</div>
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<div class="line n31">31</div>
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<div class="line n32">32</div>
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<div class="line n33">33</div>
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<div class="line n40">40</div>
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<div class="line n44">44</div>
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<div class="line n45">45</div>
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<div class="line n46">46</div>
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<div class="line n47">47</div>
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<div class="line n48">48</div>
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<div class="line n49">49</div>
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<div class="line n50">50</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></code></div></div><div class="container"><div class="line"><code> <span class="tag">div</span> <span class="rules">{ <span class="rule"><span class="attribute">width</span>:<span class="value"><span class="number">40</span>px;</span></span> <span class="rule"><span class="attribute">height</span>:<span class="value"><span class="number">40</span>px;</span></span> <span class="rule"><span class="attribute">margin</span>:<span class="value"><span class="number">10</span>px;</span></span> <span class="rule"><span class="attribute">float</span>:<span class="value">left;</span></span></span></code></div></div><div class="container"><div class="line"><code> <span class="rule"><span class="attribute">border</span>:<span class="value"><span class="number">2</span>px solid blue;</span></span> <span class="rule">}</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">red;</span></span> <span class="rule"><span class="attribute">font-weight</span>:<span class="value">bold;</span></span> <span class="rule">}</span></span></code></div></div><div class="container"><div class="line"><code> <span class="tag">button</span> <span class="rules">{ <span class="rule"><span class="attribute">margin</span>:<span class="value"><span class="number">5</span>px;</span></span> <span class="rule">}</span></span></code></div></div><div class="container"><div class="line"><code> <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">button</span>></span>Turn slice yellow<span class="tag"></<span class="title">button</span>></span></code></div></div><div class="container"><div class="line"><code> <span class="tag"><<span class="title">span</span>></span>Click the button!<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">div</span>></span><span class="tag"></<span class="title">div</span>></span></code></div></div><div class="container"><div class="line"><code> <span class="tag"><<span class="title">div</span>></span><span class="tag"></<span class="title">div</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">div</span>></span><span class="tag"></<span class="title">div</span>></span></code></div></div><div class="container"><div class="line"><code> <span class="tag"><<span class="title">div</span>></span><span class="tag"></<span class="title">div</span>></span></code></div></div><div class="container"><div class="line"><code> <span class="tag"><<span class="title">div</span>></span><span class="tag"></<span class="title">div</span>></span></code></div></div><div class="container"><div class="line"><code> <span class="tag"><<span class="title">div</span>></span><span class="tag"></<span class="title">div</span>></span></code></div></div><div class="container"><div class="line"><code> <span class="tag"><<span class="title">div</span>></span><span class="tag"></<span class="title">div</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">div</span>></span><span class="tag"></<span class="title">div</span>></span></code></div></div><div class="container"><div class="line"><code> <span class="tag"><<span class="title">div</span>></span><span class="tag"></<span class="title">div</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></code></div></div><div class="container"><div class="line"><code><span class="function"><span class="keyword">function</span> <span class="title">colorEm</span><span class="params">()</span> {</span></code></div></div><div class="container"><div class="line"><code> <span class="keyword">var</span> $div = $(<span class="string">"div"</span>);</code></div></div><div class="container"><div class="line"><code> <span class="keyword">var</span> start = Math.floor(Math.random() *</code></div></div><div class="container"><div class="line"><code> $div.length);</code></div></div><div class="container"><div class="line"><code> <span class="keyword">var</span> end = Math.floor(Math.random() *</code></div></div><div class="container"><div class="line"><code> ($div.length - start)) +</code></div></div><div class="container"><div class="line"><code> start + <span class="number">1</span>;</code></div></div><div class="container"><div class="line"><code> <span class="keyword">if</span> (end == $div.length) end = <span class="literal">undefined</span>;</code></div></div><div class="container"><div class="line"><code> $div.css(<span class="string">"background"</span>, <span class="string">""</span>);</code></div></div><div class="container"><div class="line"><code> <span class="keyword">if</span> (end)</code></div></div><div class="container"><div class="line"><code> $div.slice(start, end).css(<span class="string">"background"</span>, <span class="string">"yellow"</span>);</code></div></div><div class="container"><div class="line"><code> <span class="keyword">else</span></code></div></div><div class="container"><div class="line"><code> $div.slice(start).css(<span class="string">"background"</span>, <span class="string">"yellow"</span>);</code></div></div><div class="container"><div class="line"><code> </code></div></div><div class="container"><div class="line"><code> $(<span class="string">"span"</span>).text(<span class="string">'$("div").slice('</span> + start +</code></div></div><div class="container"><div class="line"><code> (end ? <span class="string">', '</span> + end : <span class="string">''</span>) +</code></div></div><div class="container"><div class="line"><code> <span class="string">').css("background", "yellow");'</span>);</code></div></div><div class="container"><div class="line"><code>}</code></div></div><div class="container"><div class="line"><code> </code></div></div><div class="container"><div class="line"><code>$(<span class="string">"button"</span>).click(colorEm);</code></div></div><div class="container"><div class="line"><code><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" data-height="240"></div>
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</div>
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<div class="entry-example" id="example-1">
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<h4>Example: <span class="desc">假设共有三个段落，选择所有的段落，并进行 slice 操作，选择的范围只包含第一个元素。</span>
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</h4>
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<div class="syntaxhighlighter javascript ">
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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">"p"</span>).slice(<span class="number">0</span>, <span class="number">1</span>).wrapInner(<span class="string">"<b></b>"</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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</div>
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<div class="entry-example" id="example-2">
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<h4>Example: <span class="desc">假设共有三个段落，选择所有的段落，并进行 slice 操作，选择的范围只包含第一个和第二个元素。</span>
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</h4>
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<div class="syntaxhighlighter javascript ">
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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>$(<span class="string">"p"</span>).slice(<span class="number">0</span>, <span class="number">2</span>).wrapInner(<span class="string">"<b></b>"</span>);</code></div></div></pre>
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</td>
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</tr>
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</table>
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</div>
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</div>
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<div class="entry-example" id="example-3">
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<h4>Example: <span class="desc">假设共有三个段落，选择所有的段落，并进行 slice 操作，选择的范围只包含第二个元素。</span>
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</h4>
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<div class="syntaxhighlighter javascript ">
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<table>
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<tbody>
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<tr>
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<td class="gutter">
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<div class="line n1">1</div>
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</td>
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<td class="code">
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<pre><div class="container"><div class="line"><code>$(<span class="string">"p"</span>).slice(<span class="number">1</span>, <span class="number">2</span>).wrapInner(<span class="string">"<b></b>"</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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</div>
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<div class="entry-example" id="example-4">
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<h4>Example: <span class="desc">假设共有三个段落，选择所有的段落，并进行 slice 操作，选择的范围只包含第二个和第三个元素。</span>
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</h4>
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<div class="syntaxhighlighter javascript ">
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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>$(<span class="string">"p"</span>).slice(<span class="number">1</span>).wrapInner(<span class="string">"<b></b>"</span>);</code></div></div></pre>
|
||
</td>
|
||
</tr>
|
||
</tbody>
|
||
</table>
|
||
</div>
|
||
</div>
|
||
<div class="entry-example" id="example-5">
|
||
<h4>Example: <span class="desc">假设共有三个段落，选择所有的段落，并进行 slice 操作，选择的范围只包含第三个元素。</span>
|
||
</h4>
|
||
<div class="syntaxhighlighter javascript ">
|
||
<table>
|
||
<tbody>
|
||
<tr>
|
||
<td class="gutter">
|
||
<div class="line n1">1</div>
|
||
</td>
|
||
<td class="code">
|
||
<pre><div class="container"><div class="line"><code>$(<span class="string">"p"</span>).slice(-<span class="number">1</span>).wrapInner(<span class="string">"<b></b>"</span>);</code></div></div></pre>
|
||
</td>
|
||
</tr>
|
||
</tbody>
|
||
</table>
|
||
</div>
|
||
</div></section>
|
||
</div></article> </div>
|
||
</article> |