Simple code that disables the mouse-left key function on a Web page

Web page to prohibit the mouse left and right key function of the simple code this code used to find on the Internet, the trial effect is good, put here to leave a backup, I think this can be regarded as one of the common code. Of course, look at the source of the mouse can certainly use it, but sometimes do not think so complex, demanding so strong, and the source code more than the text.
<script language=javascript> document.oncontextmenu=new Function ("event.returnvalue=false;"); Document.onselectstart=new Function ("event.returnvalue=false;"); </script> Web page prevents the mouse key function of simple code