<html>
<head>
<script type="text/javascript">
function changeTarget()
{
document.getElementById('venus').target="_blank"
}
</script>
</head>
<body>
<img src ="/img/eg_planets.jpg"
alt="Planets"
usemap ="#planetmap" />
<map name ="planetmap">
<area shape ="circle" coords ="180,139,14"
href ="/example/hdom/venus.html" id="venus" />
</map>
<br />
<input type="button" onclick="changeTarget()"
value="更改 target" />
</body>
</html>