Knockout - Lazy data loading into observables

ko.ext.lazy.js

// thanks to rniemeyer!
// http://www.knockmeout.net/2011/06/lazy-loading-observable-in-knockoutjs.html

ko.extenders.lazy = function(target, callback){
	
	var result = ko.computed({
		read: function(){
			if (!result.loaded()) callback.call(context);
			return target();
		},
		write: function(newValue){
			result.loaded(true);
			target(newValue);
		},
		deferEvaluation: true
	});
	
	result.loaded = ko.observable(false);
	result.refresh = function(){ result.loaded(false); };
	
	return result;
}