My standalone cross browser "DOM is ready" function.

domready.js

// Standalone DOM ready utility function
// Parts lifted from the following places:
// https://code.jquery.com/jquery-1.9.1.js
// https://github.com/ded/domready/blob/master/ready.js

// usage:
// domReady(function() { console.log('DOM is ready!'); });
// domReady(function() { console.log('Another method called upon DOM being ready'); });

(function(win,doc) {
	var docEl = doc.documentElement,
		readyHandlerList,
		realEventModel = !!win.addEventListener,
		readyStateRegExp = /^(loade|c)/,
		DOMIsReady = readyStateRegExp.test(doc.readyState),
		DOMContentLoadedEvent = 'DOMContentLoaded',
		onReadyStateChangeEvent = 'onreadystatechange';

	win.domReady = function(handler) {
		// if DOM ready call handler right away
		if (DOMIsReady) return handler();

		if (!readyHandlerList) {
			// init events
			if (realEventModel) {
				doc.addEventListener(DOMContentLoadedEvent,readyHandler,false);
				win.addEventListener('load',readyHandler,false);

			} else {
				// Internet Explorer event model
				doc.attachEvent(onReadyStateChangeEvent,readyHandler);
				win.attachEvent('onload',readyHandler);

				// doScroll() hack for Internet Explorer < 9, (it should) fire earlier than 'onreadystatechange'
				// this will fail (badly) if used inside an iframe - so don't
				if (docEl.doScroll) {
					(function doScrollCheck() {

						if (!DOMIsReady) {
							try {
								docEl.doScroll('left');

							} catch (e) {
								return setTimeout(doScrollCheck,50);
							}

							DOMIsReady = true;
							readyHandler();
						}
					})();
				}
			}

			readyHandlerList = [];
		}

		// add handler to stack
		readyHandlerList.push(handler);
	};

	function readyHandler(event) {
		if (realEventModel || DOMIsReady || (event.type == 'load') || (readyStateRegExp.test(doc.readyState))) {
			// detach events
			if (realEventModel) {
				doc.removeEventListener(DOMContentLoadedEvent,readyHandler,false);
				win.removeEventListener('load',readyHandler,false);

			} else {
				doc.detachEvent(onReadyStateChangeEvent,readyHandler);
				win.detachEvent('onload',readyHandler);
			}

			// process handler stack
			while (readyHandlerList.length) readyHandlerList.shift()();
			DOMIsReady = true;
		}
	}
})(window,document);