Use javascript to position the mouse position in firefox_javascript skills

/**
* Get mouse coordinates
* @return Position
*/ 
function getMouseLocation(){ 
if(ns4||ns6){ 
mouseX = e.pageX; 
mouseY = e.pageY; 
} 
else{ 
mouseX = event.x   document.body.scrollLeft; 
mouseY = event.y   document.body.scrollTop; 
} 
return {x:mouseX,y:mouseY}; 
} 
在strict下document.body要改成document.documentElement