how to disable right click on images

this is script for disable right click on images for html pages.


  <script language="JavaScript">

var clickmessage="Right click disabled on images!"

function disableclick(e)

{

if (document.all)

{

if (event.button==2||event.button==3)

     

{

if (event.srcElement.tagName=="IMG")

{

alert(clickmessage);

                  return false;

}

}

}

else if (document.layers)

{

if (e.which == 3)

{

alert(clickmessage);

return false;

}

}

else if (document.getElementById)

{

if (e.which==3&&e.target.tagName=="IMG")

{

            alert(clickmessage)

return false

}

}

}

function associateimages()

{

for(i=0;i<document.images.length;i++)

document.images[i].onmousedown=disableclick;

}

if (document.all)

{

document.onmousedown=disableclick

}

else if (document.getElementById)

{

document.onmouseup=disableclick

}

else if (document.layers)

{

associateimages()

}

</script>