Load and cache scripts and styles with localStorage

cache.js

(function (NAME, LISTENER, HEAD) {
	window[NAME] = function (src, node, loading) {
		var
		// prepare cache
		key = NAME + ':' + src,
		cache = localStorage[key] || '',
		name = parseFloat(cache[0]) ? 'script' : 'style',
		x, xhr;

		// if cache exists
		if (cache) {
			// append cache
			x = document.createElement('x');

			x.innerHTML = '<' + name + '>' + cache.slice(1) + '</' + name + '>';

			if (node) HEAD.removeChild(node);

			node = x.lastChild;

			HEAD.appendChild(node);
		}

		// if document is ready
		if (/t/.test(document.readyState) && !loading) {
			// load resource
			xhr = new XMLHttpRequest();

			xhr.open('GET', src);

			xhr.onload = function () {
				// save resource to cache
				localStorage[key] = (/javascript|json/.test(xhr.getResponseHeader('content-type')) ? 1 : 0) + xhr.responseText;

				// rerun
				window[NAME](src, node, true);
			};

			xhr.send();
		} else {
			// rerun on window load
			window[LISTENER[0]](LISTENER[1] + 'load', function () {
				window[NAME](src);
			});
		}
	};
})(
	'cache',
	'addEventListener' in window ? ['addEventListener', ''] : ['attachEvent', 'on'],
	document.getElementsByTagName('head')[0]
);