function addEvent(element, trigger, action)

addEvent.js

/**
 * Add a event to a element;
 * @param {Object} element	Element or ID;
 * @param {String} trigger	Trigger to fire action eg:load,click,mouseover,etc;
 * @param {Function} action	A pointer to a function to be called on trigger;
 */
function addEvent(element, trigger, action){
	if(typeof element==="string"){element=document.getElementById(element);}
	if(element.addEventListener){
		element.addEventListener(trigger,action,false);
		return true;
	}
	else if(element.attachEvent){
		element['e'+trigger+action] = action;
		element[trigger+action] = function() { element['e'+trigger+action]( window.event );}
		var r = element.attachEvent('on'+trigger, element[trigger+action]);
		return r;
	}
	else{
		element['on'+trigger] = action;
		return true;
	}
}