Render Handlebars templates from a server-side resource with caching to session storage

gistfile1.js

/*
 * This decorates Handlebars.js with the ability to load
 * templates from an external source, with light caching.
 * 
 * To render a template, pass a closure that will receive the 
 * template as a function parameter, eg, 
 *   T.render('template-name', function(t) {
 *       $('#somediv').html( t() );
 *   });
 */
var Template = function() {
	this.cached = {};
	this.hasSessionStorage = !!window.sessionStorage;
};
var T = new Template();
$.extend(Template.prototype, {
	render: function(name, callback) {
		if (T.isCached(name)) {
			callback(T.getFromCache(name));
		} else {
			$.get(T.urlFor(name), function(raw) {
				T.store(name, raw);
				T.render(name, callback);
			});
		}
	},
	renderSync: function(name, callback) {
		if (!T.isCached(name)) {
			T.fetch(name);
		}
		T.render(name, callback);
	},
	prefetch: function(name) {
		if (!T.isCached) {
			$.get(T.urlFor(name), function(raw) { 
				T.store(name, raw);
			});
		}
	},
	fetch: function(name) {
		// synchronous, for those times when you need it.
		if (! T.isCached(name)) {
			var raw = $.ajax({'url': T.urlFor(name), 'async': false}).responseText;
			T.store(name, raw);			
		}
	},
	getFromCache: function(name) {
		if (T.hasSessionStorage) {
			var cached = window.sessionStorage.getItem("template-" + name);
			if (!!cached) {
				return Handlebars.compile(cached);				
			} else {
				return cached;
			}
		} else {
			return T.cached[name];
		}		
	},
	isCached: function(name) {
		return !!this.getFromCache(name);
	},
	store: function(name, raw) {
		if (T.hasSessionStorage) {
			window.sessionStorage.setItem("template-" + name, raw);			
		} else {
			T.cached[name] = Handlebars.compile(raw);			
		}
	},
	urlFor: function(name) {
		return "/resources/templates/"+ name + ".handlebars";
	}
});