<!DOCTYPE html>
<html>
<body>
<img src="planets.gif" width="145" height="126" usemap="#planetmap">
<map name="planetmap">
<area id="venus" shape="circle" coords="124,58,8" alt="Venus" href="venus.htm">
</map>
<p>Click the button to display the port of the href attribute for the "venus" area in the image-map.</p>
<p><b>Note:</b> If the port part is not specified in the URL, or if the port number is 80 (which is default), some browsers will just display 0 or nothing.</p>
<button onclick="myFunction()">Try it</button>
<p id="demo"></p>
<script>
function myFunction() {
var x = document.getElementById("venus").port;
document.getElementById("demo").innerHTML = "Port: " + x;
}
</script>
</body>
</html>