第四章笔记：
如何让一个a标签不跳转：
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN"
"http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en">
<head>
<meta http-equiv="content-type" content="text/html; charset=utf-8" />
<title>Image Gallery</title>
</head>
<body>
<h1>Snapshots</h1>
<ul>
<li>
<a href="http://www.baidu.com" title="A fireworks display" onclick="return false;">点击跳转</a>//实现不跳转
</li>
<li>
<a href="images/fireworks.jpg" title="A fireworks display" onclick="showPic(this); return false;">Fireworks</a>
</li>
</ul>
<img id="placeholder" src="images/placeholder.gif" alt="my image gallery" />
</body>
</html>
<a href="http://www.baidu.com" title="A fireworks display" onclick="return false;">点击跳转</a>//实现不跳转