代码示例：（标识：eg_js_events_imagemap）
<!DOCTYPE html>
<html>
<head>
<script>
function writeText(txt) {
document.getElementById("desc").innerHTML = txt;
}
</script>
</head>
<body>
<img src ="/static/demo/images/eg_planets.jpg"
alt="Planets"
usemap ="#planetmap" />
<map name="planetmap">
<area shape ="rect" coords ="0,0,108,260"
onmouseover="writeText('太阳和像木星这样的天然气巨行星是迄今为止太阳系中最大的天体。')"
href ="/demo/planets_sun.html" target ="_blank" alt="Sun" />
<area shape ="circle" coords ="129,162,9"
onmouseover="writeText('水星很难从地球上研究，因为它总是如此接近太阳。')"
href ="/demo/planets_mercur.html" target ="_blank" alt="Mercury" />
<area shape ="circle" coords ="180,139,14"
onmouseover="writeText('直到 20 世纪 60 年代，金星经常被认为是地球的孪生姐妹，因为金星是离我们最近的行星，因为这两个行星似乎有许多共同的特征。')"
href ="/demo/planets_venus.html" target ="_blank" alt="Venus" />
</map>
<p id="desc">将鼠标悬停在太阳和火星上，看看不同的描述。</p>
</body>
</html>
