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<title>Bubble in JavaScript DOM</title>
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<h1>Bubble in JavaScript DOM</h1>
<p>DOM树的结构是：</p>
<pre><code>
UL
- LI
- A
- SPAN
</code></pre>
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<ul>
<li><a href="#"><span>阿秀</span></a></li>
<li><a href="#"><span>阿秀</span></a></li>
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<p>鼠标进入UL的任何一个子元素，如果不停止冒泡，我们从UL到SPAN都定义了鼠标悬停（<code>mouseover</code>）事件，这个事件会上升了UL，从而从鼠标所进入的元素到UL元素都会有红色的边。</p>
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<li><a href="#"><span>俊秀</span></a></li>
<li><a href="#"><span>俊秀</span></a></li>
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<p>如果停止冒泡，事件不会上升，我们就可以获取精确的鼠标进入元素。</p>
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