<html>
<head>
<script type="text/javascript">
function changeLink()
{
document.getElementById('venus').href="//www.w3xue.com"
}
</script>
</head>
<body>
<p>请点击金星（Venus）：</p>
<img src="/img/eg_planets.jpg"
usemap="#planetmap" />
<map name="planetmap">
<area
id="venus"
shape="circle"
coords="180,139,14"
href ="/example/html/venus.html"
alt="Venus" />
</map>
<input type="button" onclick="changeLink()" value="改变链接" />
</body>
</html>