From http://www.w3schools.com (Copyright Refsnes Data)

JavaScript Image Maps

An image-map is an image with clickable regions.

Examples

HTML Image Maps

From our HTML tutorial we have learned that an image-map is an image with clickable regions. Normally, each region has an associated hyperlink. Clicking on one of the regions takes you to the associated link.

Example

The example below demonstrates how to create an HTML image map, with clickable regions. Each of the regions is a hyperlink:

<img src ="planets.gif"
width ="145" height ="126"
alt="Planets"
usemap ="#planetmap" />

<map id ="planetmap"
name="planetmap">
<area shape ="rect" coords ="0,0,82,126"
  href ="sun.htm" target ="_blank"
  alt="Sun" />
<area shape ="circle" coords ="90,58,3"
  href ="mercur.htm" target ="_blank"
  alt="Mercury" />
<area shape ="circle" coords ="124,58,8"
  href ="venus.htm" target ="_blank"
  alt="Venus" />
</map>

Result

Adding some JavaScript

We can add events (that can call a JavaScript) to the <area> tags inside the image map. The <area> tag supports the onClick, onDblClick, onMouseDown, onMouseUp, onMouseOver, onMouseMove, onMouseOut, onKeyPress, onKeyDown, onKeyUp, onFocus, and onBlur events.

Here's the above example, with some JavaScript added:

<html>
<head>
<script type="text/javascript">
function writeText(txt)
{
document.getElementById("desc").innerHTML=txt;
}
</script>
</head>

<body>
<img src="planets.gif" width="145" height="126"
alt="Planets" usemap="#planetmap" />

<map id ="planetmap" name="planetmap">
<area shape ="rect" coords ="0,0,82,126"
onMouseOver="writeText('The Sun and the gas giant
planets like Jupiter are by far the largest objects
in our Solar System.')"
href ="sun.htm" target ="_blank" alt="Sun" />

<area shape ="circle" coords ="90,58,3"
onMouseOver="writeText('The planet Mercury is very
difficult to study from the Earth because it is
always so close to the Sun.')"
href ="mercur.htm" target ="_blank" alt="Mercury" />

<area shape ="circle" coords ="124,58,8"
onMouseOver="writeText('Until the 1960s, Venus was
often considered a twin sister to the Earth because
Venus is the nearest planet to us, and because the
two planets seem to share many characteristics.')"
href ="venus.htm" target ="_blank" alt="Venus" />
</map> 

<p id="desc"></p>

</body>
</html>