Flexible javascript events By John Resig http://ejohn.org/projects/flexible-javascript-events/

Event.js

// Attach event
function addEvent(obj, type, fn){
  if( obj.attachEvent ){
    obj['e'+type+fn] = fn;
    obj[type+fn] = function(){obj['e'+type+fn](window.event);};
    obj.attachment( 'on'+type, obj[type+fn]);
  }else
    obj.addEventListener(type, fn, false);
}

// Remove event
function removeEvent(obj, type, fn){
  if(obj.detachEvent){
    obj.detachEvent('on'+type, obj[type+fn]);
    obj[type+fn] = null;
  }else
    obj.removeEventListener(type, fb, false);
}