state.js - browser history and bookmarks for ajax apps

state.js

/**
 * Copyright (c) 2012, ESHA Research
 * Dual licensed under the MIT and GPL licenses:
 *   http://www.opensource.org/licenses/mit-license.php
 *   http://www.gnu.org/licenses/gpl.html
 *
 * @version 0.4
 * @requires jQuery
 * @name state
 * @author Nathan Bubna
 */
;(function($, window, $doc, location, history) {
    
    var state = window.state = function(id, arg, e) {
        return !id ? $.extend({}, _state) :
            arg === undefined ? state.of(id, e) :
            $.isFunction(arg) ? state.bind(id, arg) :
            state.set(id, arg, e);
    },
    _state = {};
    state.of = function(id, e) {
        var is = state.get(id),
            was = _state[id];
        if (!is && !(id in _state)) {
            is = state.get(id, true);// check hash for new ids
        }
        if ((is || was) && is !== was) {
            _state[id] = is;
            $doc.trigger(id+'.state', is, was, e);
        }
        return is;
    };
    state.ofAll = function(e) {
        for (var id in _state) state.of(id, e);
    };
    state.bind = function(id, fn) {
        $doc.on(id+'.state', fn);
        return state.of(id);// track this id
    };

    state.get = function(id, hash) {
        var re = new RegExp('&?'+id+'=([^&#;$]+)'),
            val = state.getAll(hash).match(re) || '';
        return val && decodeURIComponent(val[1].replace(/\+/g, '%20'));
    };
    state.set = function(id, val) {
        val = val === undefined || val === null ? '' : ''+val;
        if (val !== _state[id]) {
            _state[id] = val;
            var pair = val ? id+'='+val : '',
                re = new RegExp('&?'+id+'=[^&#;$]*&?'),
                rest = state.getAll().replace(re, '');
            if (pair && rest) pair += '&';
            state.setAll(pair+rest);
        }
    };
    state.getAll = function(hash) {
        var part = state.hash || hash ? location.hash : location.search;
        return part && part.length > 1 ? part.substring(1) : '';
    };
    state.setAll = function(s) {
        history.pushState(null,'', '?'+s+location.hash); // keep hash to play nice
    };

    $doc
    .on('state.state', function(e, id, val){ state(id, val, e); })
    .on('back.state', function(){ history.back(); })
    .on('forward.state', function(){ history.forward(); });
    if ('history' in window && 'pushState' in history) {
        $(window).on('popstate.state', state.ofAll);
    } else {
        state.hash = true;
        state.setAll = function(s){ location.hash = s; }
        $(window).on('hashchange.state', state.ofAll);
    }

})(jQuery, window, $(document), window.location, window.history);