javascript事件冒泡简单示例

时间:2020-05-15 cherry 人气:0
本文实例讲述了javascript事件冒泡的定义与用法。分享给大家供大家参考，具体如下：
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" lang="zh" xml:lang="zh">
 <head>
  <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
  <meta name="developer" content="Realazy" />
  <title>Bubble in JavaScript DOM</title>
  <style type="text/css" media="screen">
   div * {
    display: block;
    margin: 4px;
    padding: 4px;
    border: 1px solid white;
   }
   textarea {
    width: 20em;
    height: 2em;
   }
  </style>
  <script type="text/javascript">
   //<![CDATA[
   function init(){
    var log = document.getElementsByTagName('textarea')[0];
    var all = document.getElementsByTagName('div')[0].getElementsByTagName('*');
    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;
     };
     all[i].onmouseout = function(e){
      this.style.border = '1px solid white';
     };
    }
    var all2 = document.getElementsByTagName('div')[1].getElementsByTagName('*');
    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;
     };
     all2[i].onmouseout = function(e){
      this.style.border = '1px solid white';
     };
    }
   }
   window.onload = init;
   //]]>
  </script>
 </head>
 <body>
  <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="//www.qb5200.com/#"><span>Bubbllllllllllllllle</span></a>
    </li>
    <li>
     <a href="//www.qb5200.com/#"><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="//www.qb5200.com/#"><span>Bubbllllllllllllllle</span></a>
    </li>
    <li>
     <a href="//www.qb5200.com/#"><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>
 </body>
</html>
希望本文所述对大家JavaScript程序设计有所帮助。
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