IE 和 FF下禁用Ctrl键

<script type="text/javascript">
function stopCtrl(e)
{
var keyCode = e.keyCode?e.keyCode:e.which?e.which:e.charCode;
if (keyCode==17){
if(!e.which){
e.keyCode=0;
e.cancelBubble = true;//禁用冒泡
e.returnValue=false;
}else{
if (e.stopPropagation) {
e.stopPropagation();
e.preventDefault();
}
}

}
</script>