更新鼠标位置,兼容IE跟FF

//更新鼠标位置
var mousePos = {x:0,y:0};
function mouseCoords(ev){ 
	ev= ev || window.event; 
	if(ev.pageX || ev.pageY){ 
		mousePos = {x:ev.pageX+10, y:ev.pageY+10}; 
	} 
	mousePos = { 
		x:ev.clientX + document.documentElement.scrollLeft - document.body.clientLeft+10,
		y:ev.clientY + document.documentElement.scrollTop   - document.body.clientTop+10
	}; 
}