<!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 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="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> </body> </html>
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