Add A New Function To An Event Handler

I try to add a function to be triggered also within an event (which already has a function). I coded it, unfortunatelly one line of the code should be different for IE and Moz. I try to find a common way without using a browser detector... Any ideea? The red line works for Mozilla, the blue one for IE:

function addFunc(){
var e = document.getElementsByTagName('*');
for(var i=0;i<e.length;i++){
if(e[i].getAttribute('onclick')||e[i].getAttribute('onclick')!=null){// Moz || IE
//var f = new Function(e[i].getAttribute('onclick'));
var f = e[i].getAttribute('onclick');
e[i].onclick=function(){f();otherFunction()}
}}} Code: