JavaScript 的事件冒泡 demo

来源：Realazy 作者：Realazy 2007-12-03 出处：pcdog.com

xml

如果你还不理解JavaScript的事件冒泡往下看：

运行代码框

<!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="#"><span>Bubbllllllllllllllle</span></a></li>
		<li><a href="#"><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="#"><span>Bubbllllllllllllllle</span></a></li>
		<li><a href="#"><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>

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