jquery.hashable.js

/*!
* Hashable jQuery plugin
* http://www.thepiepers.net/
*
* This jQuery plugin enables a website owner to easily bind to the hash value changes.
* If the Modernizr v2.0+ library is present and the browser supports the hashchange event,
* it will fire based on change, rather than timer.
*
* Usage:
* <script type="text/javascript">
*  // the callback will receive the new and old hash values as arguments
*  $(window).hashChange(callbackFunction);
*  
*  // or you can bind to the "hashChange" event
*  $(window).bind("hashChange", function(e, newHash, oldHash) {
*      console.log("new: " +  newHash);
*      console.log("old: " + oldHash);
*  });
* </script>
*
* Copyright (c) 2011, Bryan Pieper
* Released under the MIT license.
* http://www.opensource.org/licenses/mit-license.php
*/

(function($) {

	$.fn.hashChange = function(func, options) {
		
		var settings = {
			initialHash: "",
			delay: 100
		};
		
		var timer = null;
		var lastHashValue = "";
		var $this = $(this);
		
		if (typeof options !== "undefined") {
			$.extend(settings, options);
		}

		function parseHash(val) {
			if (!val) { 
				val = "";
			} else {
				if (val.substring(0, 1) == "#") {
					val = val.substring(1);
				}
			}
			return val;
		}
		
		function getCurrentHashValue() {
			return parseHash(window.location.hash);
		}
		
		function checkHash() {
			// check current hash state
			var currentHash = getCurrentHashValue();
			if (currentHash != lastHashValue) {
				var lastHashValue2 = lastHashValue;
				
				// reset known hash
				lastHashValue = currentHash;
				
				// fire hashChange event
				$this.trigger("hashChange", [currentHash, lastHashValue2]);
				
				if (typeof func !== "undefined") {
					// hashchange callback: new, old
					func(currentHash, lastHashValue2)
				}
			}
		}
		
		// override initial hash
		lastHashValue = parseHash(settings.initialHash);

		// Modernizr check
		if (typeof Modernizr !== "undefined" && Modernizr.hashchange) {
			// bind to window event change
			$this.bind("hashchange", checkHash);

			// call initial hashChange for page load
			checkHash();
		} else {
			timer = setInterval(checkHash, settings.delay);
		}
		
	};
	
})(jQuery);