JavaScript 事件冒泡机制详解与示例

示例代码与停止冒泡

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  <meta name="developer" content="Realazy" />
  <title>Bubble in JavaScript DOM</title>
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    for (var i = 0, n = all.length; i < n; ++i) {
     all[i].onmouseover = function(e){
      this.style.border = '1px solid red';
      log.value = '鼠标现在进入的是： ' + this.nodeName;
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    for (var i = 0, n = all2.length; i < n; ++i) {
     all2[i].onmouseover = function(e){
      this.style.border = '1px solid red';
      if (e) //停止事件冒泡
       e.stopPropagation();
      else 
       window.event.cancelBubble = true;
      log.value = '鼠标现在进入的是： ' + this.nodeName;
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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>
  <div>
   <ul>
    <li>
     <a href="https://www.jb51.net/#"><span>Bubbllllllllllllllle</span></a>
    </li>
    <li>
     <a href="https://www.jb51.net/#"><span>Bubbllllllllllllllle</span></a>
    </li>
   </ul>
  </div>
  <textarea>
  </textarea>
  <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>
  <div>
   <ul>
    <li>
     <a href="https://www.jb51.net/#"><span>Bubbllllllllllllllle</span></a>
    </li>
    <li>
     <a href="https://www.jb51.net/#"><span>Bubbllllllllllllllle</span></a>
    </li>
   </ul>
  </div>
  <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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