有时候为了保护网站的图片不被其它网站下载使用，可以用代码禁止下载，代码如下：

<script language="JavaScript1.2">
/*
Disable right click script II (on images)- By Dynamicdrive.com
For full source, Terms of service, and 100s DTHML scripts
Visit http://www.dynamicdrive.com
*/
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;
}
}
}
if (document.layers) {
if (e.which == 3) {
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.layers)
associateimages()
</script>
<img src="#">