Disabling left click on a web page

This script will disable thr right click function on a web page.

<!-- this script got from www.javascriptfreecode.com-Coded by: Krishna Eydat -->
<SCRIPT LANGUAGE="JavaScript">
var message="Function Disabled!";
///////////////////////////////////
function clickIE() {if (document.all) {alert(message);return false;}}
function clickNS(e) {if
(document.layers||(document.getElementById&&!document.all)) {
if (e.which==2||e.which==3) {alert(message);return false;}}}
if (document.layers)
{document.captureEvents(Event.MOUSEDOWN);document.onmousedown=clickNS;}
else{document.onmouseup=clickNS;document.oncontextmenu=clickIE;}

document.oncontextmenu=new Function("return false")
// -->
</script>
<font face="Tahoma"><a target="_blank" href="http://www.javascriptfreecode.com/"><span style="font-size: 8pt; text-decoration: none">JavaScript Free Code</span></a></font>

Hopefully this article is helpful.

Taken from here