代码示例：（标识：hdom_image_usemap）
<html>
<body>
<img id="planets"
src="/static/demo/images/eg_planets.jpg"
usemap="#planetmap" />
<map name="planetmap">
<area
shape="circle"
coords="180,139,14"
href ="/static/demo/html/venus.html"
target ="_blank"
alt="Venus" />
</map>
<p>单击按钮以显示图像的 usemap 属性的值。</p>
<button onclick="myFunction()">试一试</button>
<p id="demo"></p>
<script>
function myFunction() {
var x = document.getElementById("planets").useMap;
document.getElementById("demo").innerHTML = x;
}
</script>
</body>
</html>
