I hope I used a proper title.

I'm having difficulties with finding the proper atribut of an object with DOM. Like this example, which works on IE, Opera has hiccups, but in NS and Mozilla doesn't work at all (I'll show just the important parts):

<body bgcolor="white" onmousemove="move();">
<div id="moj1"></div> <!-- which has styles defined. positioning included -->

function dom(objectID) {return document.getElementById(objectID).style;}
function findYCoord(evt) {
if (evt.y) return evt.y;
if (evt.pageY) return evt.pageY;}

function findXCoord(evt) {
if (evt.x) return evt.x;
if (evt.pageX) return evt.pageX;}

function move() { dom('moj1').left = findXCoord(event);
dom('moj1').top = findYCoord(event);}


So I guess x or pageX doesn't work in NS. Which does?
Do you use any conventions or programs or whatever to find out which properties in javascript does it support on different browsers?