hashArgs

/**
 ** Author: Tomas E. Sandven
 **
 ** This object gives easy control over query arguments
 ** in the URL hash string
 **/

window.hashArgs = (function() {

    var self = {};
    var hash = window.location.hash.substr(1);
    var args = parseArgs(hash);

    var _changes = {};

    // Add an event to hash changed
    window.addEventListener("hashchange", function() {

        hash = window.location.hash.substr(1);
        newArgs = parseArgs(hash);

        $.each(_changes, function(e) {
            if(newArgs[e] && args[e] !== newArgs[e])
            {
                self.runChange(e, newArgs[e]);
            }
        });

        args = newArgs;
    }, false);

    // Get an argument by key
    self.get = function(key)
    {
        if(isset(key))
            return args[key];
        else return false;
    };

    // Set an argument by key
    self.set = function(key, value)
    {
        args[key] = value;
        updateHash();
    };

    // Make isset public
    self.isset = isset;

    // Add a key changed listener by name
    self.addChangeListener = function(name, callback)
    {
        if(_changes[name])
            _changes[name].push(callback);
        else
            _changes[name] = [callback];
    };

    // Run a key changed listener by name
    self.runChange = function(name, overload)
    {
        if(_changes[name])
        {
            $.each(_changes[name], function() {
                this.call(overload);
            });
        }
    }

    // Check if a key is set in args
    function isset(index)
    {
        if(typeof args[index] === "undefined")
            return false;
        else return true;
    }

    // Update the URL hash
    function updateHash()
    {
        window.location.hash = "#" + deParseHash(args);
    }

    // Parse query string to object
    function parseArgs(input)
    {
        var retval = {};
        var pairs = input.split("&");

        $.each(pairs, function(i) {
            var split = this.split("=");

            if(typeof split[1] !== "undefined")
                retval[split[0]] = split[1];

            else
                retval[split[0]] = null;
        });

        return retval;
    }

    // Object back to query string
    function deParseHash(input)
    {
        var retval = "";

        $.each(input, function(i) {
            if(i)
            {
                if(typeof this !== "null")
                    retval += "&" + i + "=" + this;
                else retval += "&" + i;
            }
        });

        return retval.substr(1);
    }

    return self;
}());