mouse.js

// Which HTML element is the target of the event
function mouseTarget(e) {
	var targ;
	if (!e) var e = window.event;
	if (e.target) targ = e.target;
	else if (e.srcElement) targ = e.srcElement;
	if (targ.nodeType == 3) // defeat Safari bug
		targ = targ.parentNode;
	return targ;
}

// Mouse position relative to the document
// From http://www.quirksmode.org/js/events_properties.html
function mousePositionDocument(e) {
	var posx = 0;
	var posy = 0;
	if (!e) {
		var e = window.event;
	}
	if (e.changedTouches) {
		var touches = e.changedTouches;
		posx = touches[0].pageX;
		posy = touches[0].pageY;
	}
	else if (e.pageX || e.pageY) {
		posx = e.pageX;
		posy = e.pageY;
	}
	else if (e.clientX || e.clientY) {
		posx = e.clientX + document.body.scrollLeft + document.documentElement.scrollLeft;
		posy = e.clientY + document.body.scrollTop + document.documentElement.scrollTop;
	}
	return {
		x : posx,
		y : posy
	};
}

// Find out where an element is on the page
// From http://www.quirksmode.org/js/findpos.html
function findPos(obj) {
	var curleft = 0,
		curtop = 0;
	if (obj.offsetParent) {
		do {
			curleft += obj.offsetLeft;
			curtop += obj.offsetTop;
		} while (obj = obj.offsetParent);
	}
	return {
		left : curleft,
		top : curtop
	};
}

// Mouse position relative to the element
// not working on IE7 and below
function mousePositionElement(e) {
	var mousePosDoc = mousePositionDocument(e);
	var target = mouseTarget(e);
	var targetPos = findPos(target);
	var posx = mousePosDoc.x - targetPos.left;
	var posy = mousePosDoc.y - targetPos.top;
	return {
		x : posx,
		y : posy
	};
}