var a;
window.document.onmousemove = function(e){
	a = getMousePosition(e).y;
}
function setPosition(){
	return a;
}
function getMousePosition(e) {
var obj = new Object();
 
if(e) {
obj.x = e.pageX;
obj.y = e.pageY;
}
else {
obj.x = event.x + document.body.scrollLeft;
obj.y = event.y + document.body.scrollTop;
}
 
return obj;
}
setPosition();