禁止网页复制

<SCRIPT LANGUAGE=javascript>
function click() {
alert('禁止你的左键复制！') }
function click1() {
if (event.button==2) {alert('禁止右键点击~！') }}
function CtrlKeyDown(){
if (event.ctrlKey) {alert('不当的拷贝将损害您的系统！') }}
document.onkeydown=CtrlKeyDown;
document.onselectstart=click;
document.onmousedown=click1;
</SCRIPT>