Javascript: addEventListener

addEventListener registers a single event listener on a single target. The event target may be a single node in a document, the document itself, a window, or an XMLHttpRequest.

In IE you have to use attachEvent rather than the standard addEventListener.

if (window.addEventListener) {
  // Mozilla, Netscape, Firefox
 el.addEventListener('onclick', function, false );
} else {
  // IE
  el.attachEvent('onclick', function);
}