javascript 禁止鼠标右键

function doProhibit()
{
	if(window.Event) 
   		document.captureEvents(Event.MOUSEUP);
		
	function nocontextmenu() 
	{
   		event.cancelBubble = true 
   		event.returnvalue = false;
   		return false;
	}
	
	function norightclick(e) 
	{
   		if (window.Event)
   		{
      		if (e.which == 2 || e.which == 3)
      		return false;
   		}
   		else if (event.button == 2 || event.button == 3) 
   		{
			event.cancelBubble = true 
			event.returnvalue = false;
			return false;
   		}
	}
	document.oncontextmenu = nocontextmenu;  // for IE5+ 
	document.onmousedown = norightclick;  // 
}