Cross Browser Event Management Functions Using JavaScript

<!doctype html public "-//w3c//dtd html 4.01 transitional//en">
<html>
<head>
<title>Cross Browser Event Management</title>
<meta http-equiv="Content-Type" content="text/html;charset=utf-8" />
<script type="text/javascript">
<!--
/*
Cross Browser Event Management
*/

function addEvent(el,evType,handle){
    if(el.addEventListener)el.addEventListener(evType,handle,false);
    else if(el.attachEvent){
        el["e"   evType   handle] = handle;
        el[evType   handle] = function(){el["e"   evType   handle](window.event)}

        el.attachEvent("on"   evType,el[evType   handle]);
    }
}

function removeEvent(el,evType,handle){
    if(el.removeEventListener)el.removeEventListener(evType,handle,false);
    else if(el.detachEvent){
        el.detachEvent("on"   evType,el[evType   handle])
        el[evType   handle] = null
        el["e"   evType   handle] = null;
    }
}
function preventDefault(evt){
    var e = evt ? evt : window.event;
    if(e.preventDefault){
        e.preventDefault();
    }else{
        e.returnValue = false;
    }
}
function stopPropagation(evt){
    var e = evt ? evt : window.event;
    if(e.stopPropagation){
        e.stopPropagation();
    }else{
        e.cancelBubble = true;
    }
}
function init(){
    addEvent(document.getElementById('ElemId'),'click',clickTest);
}
function clickTest(){
    alert('Clicked');
    removeEvent(document.getElementById('ElemId'),'click',clickTest);
    alert('Removed');
}
addEvent(window,'load',init);
//-->
</script>
</head>

<body onload="">

<div id="ElemId" style="width:200px;height:50px;border:1px #CCC solid;background:#F2F2F2;">Click Me</div>

</body>
</html>