gistfile1.js

// Lazy loading function
Function.prototype.lazyLoad = function(){
	var __method = this;
	
	function loaded(){
		loaded = __method();
		delete(__method);
		return loaded.apply(this, arguments);
	};
	return function(){
		return loaded.apply(this, arguments);
	};
};

var observe = function(){
	if (document.addEventListener)
		return function(element, eventName, callback){
			element.addEventListener(eventName, callback, false);
		};
		
	if (element.attachEvent){
		return function(element, eventName, callback){
			element.attachEvent("on" + eventName, callback);
		};
	
	return function(element, eventName, callback){
		element["on" + eventName] = callback;
	};
}.lazyLoad();

observe(document, 'load', function(){ /* ... */ }); // -> zazy load here, compiled function
observe(document, 'load', function(){ /* ... */ }); // -> compiled function
observe(document, 'load', function(){ /* ... */ }); // -> compiled function