<!DOCTYPE html>
<html>
<body>
<div onmousedown="WhichButton(event)">Click this text with one of your mouse buttons to return a number.
<p>
1 = The left mouse button<br>
2 = The right mouse button<br>
4 = The middle mouse button<br>
8 = The fourth mouse button (typically the "Browser Back" button)<br>
16 = The fifth mouse button (typically the "Browser Forward" button)<br>
</p>
</div>
<p><strong>Tip:</strong> The return values are combined if you press two buttons at once.</p>
<p><strong>Note:</strong> The buttons property is currently only supported in Firefox and IE9 and newer versions.</p>
<h2>You pressed button: <span id="demo"></span></h2>
<script>
function WhichButton(event) {
var x = event.buttons;
document.getElementById("demo").innerHTML = x;
}
</script>
</body>
</html>