hashchange.js

/*!
 * Copyright yayQuery Peoples, 2010
 *
 * Licensed under the MIT license
 * http://www.opensource.org/licenses/mit-license.php
 * 
 * This plugin is loosely based on Ben Almans BBQ Plugin, but without the extra fluff. Just
 * plain onhashchange cross-browser support through jQuery Special Event API.
 * 
 * http://yayquery.com/ - http://github.com/yayquery/
 */

(function(){
	var

	// Caching etc.
	undefined, w = window, wl = w.location,

	// Checks if the browser supports the event natively (checks all browsers except IE8,
	// which can report this as a false-positive, kudos to Ben Alman for this). We avoid using
	// Browser.Engine, we don't want to sniff that browser, yo!
	nativeSupport = ('onhashchange' in w) && !(w.console && !Browser.Features.style),

	// Used to keep track of the setInterval
	evtTimer,

	// The time, in milliseconds, we should check for hash changes
	evtPollInterval = 80,

	// Will contain the last known hash
	lastHash = wl.hash,

	// The object actually handling the simulated event, never used by the native ones.
	simulEvt = {
		start: function () {
			if (evtTimer) return;

			evtTimer = setInterval(function () {
				if (wl.hash !== lastHash) {
					w.fireEvent('hashchange');
				}

				lastHash = wl.hash;
			}, evtPollInterval);
		},

		stop: function () {
			if (!evtTimer) return;

			clearInterval(evtTimer);
			evtTimer = 0;
		}
	},

	// Curry function for invoking the simulated event (or cancel out browsers with native
	// support)
	hashFn = function (str) {
		return function () {
			if (nativeSupport) return false;
			simulEvt[str]();
		};
	};

	// Set up the special event object, tiny - innit? :-)
	$.event.special.hashchange = {
		setup:    hashFn('start'),
		teardown: hashFn('stop')
	}
	
})();