Js prohibits pages from using the simple sample code right of

Js prohibit right click code:

function click(e) {
if (document.all) {
if (event.button==1||event.button==2||event.button==3) {
oncontextmenu='return false';
}
}
if (document.layers) {
if (e.which == 3) {
oncontextmenu='return false';
}
}
}
if (document.layers) {
document.captureEvents(Event.MOUSEDOWN);
}
document.onmousedown=click;
document.oncontextmenu = new Function("return false;")