position of the mouse cursor javascript

1(function() {
2    document.onmousemove = handleMouseMove;
3    function handleMouseMove(event) {
4        var eventDoc, doc, body;
5
6        event = event || window.event; // IE-ism
7
8        // If pageX/Y aren't available and clientX/Y are,
9        // calculate pageX/Y - logic taken from jQuery.
10        // (This is to support old IE)
11        if (event.pageX == null && event.clientX != null) {
12            eventDoc = (event.target && event.target.ownerDocument) || document;
13            doc = eventDoc.documentElement;
14            body = eventDoc.body;
15
16            event.pageX = event.clientX +
17              (doc && doc.scrollLeft || body && body.scrollLeft || 0) -
18              (doc && doc.clientLeft || body && body.clientLeft || 0);
19            event.pageY = event.clientY +
20              (doc && doc.scrollTop  || body && body.scrollTop  || 0) -
21              (doc && doc.clientTop  || body && body.clientTop  || 0 );
22        }
23
24        // Use event.pageX / event.pageY here
25    }
26})();