wp/wp-includes/js/backbone.js
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     1 //     Backbone.js 1.3.3
       
     2 
       
     3 //     (c) 2010-2016 Jeremy Ashkenas, DocumentCloud and Investigative Reporters & Editors
       
     4 //     Backbone may be freely distributed under the MIT license.
       
     5 //     For all details and documentation:
       
     6 //     http://backbonejs.org
       
     7 
       
     8 (function(factory) {
       
     9 
       
    10   // Establish the root object, `window` (`self`) in the browser, or `global` on the server.
       
    11   // We use `self` instead of `window` for `WebWorker` support.
       
    12   var root = (typeof self == 'object' && self.self === self && self) ||
       
    13             (typeof global == 'object' && global.global === global && global);
       
    14 
       
    15   // Set up Backbone appropriately for the environment. Start with AMD.
       
    16   if (typeof define === 'function' && define.amd) {
       
    17     define(['underscore', 'jquery', 'exports'], function(_, $, exports) {
       
    18       // Export global even in AMD case in case this script is loaded with
       
    19       // others that may still expect a global Backbone.
       
    20       root.Backbone = factory(root, exports, _, $);
       
    21     });
       
    22 
       
    23   // Next for Node.js or CommonJS. jQuery may not be needed as a module.
       
    24   } else if (typeof exports !== 'undefined') {
       
    25     var _ = require('underscore'), $;
       
    26     try { $ = require('jquery'); } catch (e) {}
       
    27     factory(root, exports, _, $);
       
    28 
       
    29   // Finally, as a browser global.
       
    30   } else {
       
    31     root.Backbone = factory(root, {}, root._, (root.jQuery || root.Zepto || root.ender || root.$));
       
    32   }
       
    33 
       
    34 })(function(root, Backbone, _, $) {
       
    35 
       
    36   // Initial Setup
       
    37   // -------------
       
    38 
       
    39   // Save the previous value of the `Backbone` variable, so that it can be
       
    40   // restored later on, if `noConflict` is used.
       
    41   var previousBackbone = root.Backbone;
       
    42 
       
    43   // Create a local reference to a common array method we'll want to use later.
       
    44   var slice = Array.prototype.slice;
       
    45 
       
    46   // Current version of the library. Keep in sync with `package.json`.
       
    47   Backbone.VERSION = '1.3.3';
       
    48 
       
    49   // For Backbone's purposes, jQuery, Zepto, Ender, or My Library (kidding) owns
       
    50   // the `$` variable.
       
    51   Backbone.$ = $;
       
    52 
       
    53   // Runs Backbone.js in *noConflict* mode, returning the `Backbone` variable
       
    54   // to its previous owner. Returns a reference to this Backbone object.
       
    55   Backbone.noConflict = function() {
       
    56     root.Backbone = previousBackbone;
       
    57     return this;
       
    58   };
       
    59 
       
    60   // Turn on `emulateHTTP` to support legacy HTTP servers. Setting this option
       
    61   // will fake `"PATCH"`, `"PUT"` and `"DELETE"` requests via the `_method` parameter and
       
    62   // set a `X-Http-Method-Override` header.
       
    63   Backbone.emulateHTTP = false;
       
    64 
       
    65   // Turn on `emulateJSON` to support legacy servers that can't deal with direct
       
    66   // `application/json` requests ... this will encode the body as
       
    67   // `application/x-www-form-urlencoded` instead and will send the model in a
       
    68   // form param named `model`.
       
    69   Backbone.emulateJSON = false;
       
    70 
       
    71   // Proxy Backbone class methods to Underscore functions, wrapping the model's
       
    72   // `attributes` object or collection's `models` array behind the scenes.
       
    73   //
       
    74   // collection.filter(function(model) { return model.get('age') > 10 });
       
    75   // collection.each(this.addView);
       
    76   //
       
    77   // `Function#apply` can be slow so we use the method's arg count, if we know it.
       
    78   var addMethod = function(length, method, attribute) {
       
    79     switch (length) {
       
    80       case 1: return function() {
       
    81         return _[method](this[attribute]);
       
    82       };
       
    83       case 2: return function(value) {
       
    84         return _[method](this[attribute], value);
       
    85       };
       
    86       case 3: return function(iteratee, context) {
       
    87         return _[method](this[attribute], cb(iteratee, this), context);
       
    88       };
       
    89       case 4: return function(iteratee, defaultVal, context) {
       
    90         return _[method](this[attribute], cb(iteratee, this), defaultVal, context);
       
    91       };
       
    92       default: return function() {
       
    93         var args = slice.call(arguments);
       
    94         args.unshift(this[attribute]);
       
    95         return _[method].apply(_, args);
       
    96       };
       
    97     }
       
    98   };
       
    99   var addUnderscoreMethods = function(Class, methods, attribute) {
       
   100     _.each(methods, function(length, method) {
       
   101       if (_[method]) Class.prototype[method] = addMethod(length, method, attribute);
       
   102     });
       
   103   };
       
   104 
       
   105   // Support `collection.sortBy('attr')` and `collection.findWhere({id: 1})`.
       
   106   var cb = function(iteratee, instance) {
       
   107     if (_.isFunction(iteratee)) return iteratee;
       
   108     if (_.isObject(iteratee) && !instance._isModel(iteratee)) return modelMatcher(iteratee);
       
   109     if (_.isString(iteratee)) return function(model) { return model.get(iteratee); };
       
   110     return iteratee;
       
   111   };
       
   112   var modelMatcher = function(attrs) {
       
   113     var matcher = _.matches(attrs);
       
   114     return function(model) {
       
   115       return matcher(model.attributes);
       
   116     };
       
   117   };
       
   118 
       
   119   // Backbone.Events
       
   120   // ---------------
       
   121 
       
   122   // A module that can be mixed in to *any object* in order to provide it with
       
   123   // a custom event channel. You may bind a callback to an event with `on` or
       
   124   // remove with `off`; `trigger`-ing an event fires all callbacks in
       
   125   // succession.
       
   126   //
       
   127   //     var object = {};
       
   128   //     _.extend(object, Backbone.Events);
       
   129   //     object.on('expand', function(){ alert('expanded'); });
       
   130   //     object.trigger('expand');
       
   131   //
       
   132   var Events = Backbone.Events = {};
       
   133 
       
   134   // Regular expression used to split event strings.
       
   135   var eventSplitter = /\s+/;
       
   136 
       
   137   // Iterates over the standard `event, callback` (as well as the fancy multiple
       
   138   // space-separated events `"change blur", callback` and jQuery-style event
       
   139   // maps `{event: callback}`).
       
   140   var eventsApi = function(iteratee, events, name, callback, opts) {
       
   141     var i = 0, names;
       
   142     if (name && typeof name === 'object') {
       
   143       // Handle event maps.
       
   144       if (callback !== void 0 && 'context' in opts && opts.context === void 0) opts.context = callback;
       
   145       for (names = _.keys(name); i < names.length ; i++) {
       
   146         events = eventsApi(iteratee, events, names[i], name[names[i]], opts);
       
   147       }
       
   148     } else if (name && eventSplitter.test(name)) {
       
   149       // Handle space-separated event names by delegating them individually.
       
   150       for (names = name.split(eventSplitter); i < names.length; i++) {
       
   151         events = iteratee(events, names[i], callback, opts);
       
   152       }
       
   153     } else {
       
   154       // Finally, standard events.
       
   155       events = iteratee(events, name, callback, opts);
       
   156     }
       
   157     return events;
       
   158   };
       
   159 
       
   160   // Bind an event to a `callback` function. Passing `"all"` will bind
       
   161   // the callback to all events fired.
       
   162   Events.on = function(name, callback, context) {
       
   163     return internalOn(this, name, callback, context);
       
   164   };
       
   165 
       
   166   // Guard the `listening` argument from the public API.
       
   167   var internalOn = function(obj, name, callback, context, listening) {
       
   168     obj._events = eventsApi(onApi, obj._events || {}, name, callback, {
       
   169       context: context,
       
   170       ctx: obj,
       
   171       listening: listening
       
   172     });
       
   173 
       
   174     if (listening) {
       
   175       var listeners = obj._listeners || (obj._listeners = {});
       
   176       listeners[listening.id] = listening;
       
   177     }
       
   178 
       
   179     return obj;
       
   180   };
       
   181 
       
   182   // Inversion-of-control versions of `on`. Tell *this* object to listen to
       
   183   // an event in another object... keeping track of what it's listening to
       
   184   // for easier unbinding later.
       
   185   Events.listenTo = function(obj, name, callback) {
       
   186     if (!obj) return this;
       
   187     var id = obj._listenId || (obj._listenId = _.uniqueId('l'));
       
   188     var listeningTo = this._listeningTo || (this._listeningTo = {});
       
   189     var listening = listeningTo[id];
       
   190 
       
   191     // This object is not listening to any other events on `obj` yet.
       
   192     // Setup the necessary references to track the listening callbacks.
       
   193     if (!listening) {
       
   194       var thisId = this._listenId || (this._listenId = _.uniqueId('l'));
       
   195       listening = listeningTo[id] = {obj: obj, objId: id, id: thisId, listeningTo: listeningTo, count: 0};
       
   196     }
       
   197 
       
   198     // Bind callbacks on obj, and keep track of them on listening.
       
   199     internalOn(obj, name, callback, this, listening);
       
   200     return this;
       
   201   };
       
   202 
       
   203   // The reducing API that adds a callback to the `events` object.
       
   204   var onApi = function(events, name, callback, options) {
       
   205     if (callback) {
       
   206       var handlers = events[name] || (events[name] = []);
       
   207       var context = options.context, ctx = options.ctx, listening = options.listening;
       
   208       if (listening) listening.count++;
       
   209 
       
   210       handlers.push({callback: callback, context: context, ctx: context || ctx, listening: listening});
       
   211     }
       
   212     return events;
       
   213   };
       
   214 
       
   215   // Remove one or many callbacks. If `context` is null, removes all
       
   216   // callbacks with that function. If `callback` is null, removes all
       
   217   // callbacks for the event. If `name` is null, removes all bound
       
   218   // callbacks for all events.
       
   219   Events.off = function(name, callback, context) {
       
   220     if (!this._events) return this;
       
   221     this._events = eventsApi(offApi, this._events, name, callback, {
       
   222       context: context,
       
   223       listeners: this._listeners
       
   224     });
       
   225     return this;
       
   226   };
       
   227 
       
   228   // Tell this object to stop listening to either specific events ... or
       
   229   // to every object it's currently listening to.
       
   230   Events.stopListening = function(obj, name, callback) {
       
   231     var listeningTo = this._listeningTo;
       
   232     if (!listeningTo) return this;
       
   233 
       
   234     var ids = obj ? [obj._listenId] : _.keys(listeningTo);
       
   235 
       
   236     for (var i = 0; i < ids.length; i++) {
       
   237       var listening = listeningTo[ids[i]];
       
   238 
       
   239       // If listening doesn't exist, this object is not currently
       
   240       // listening to obj. Break out early.
       
   241       if (!listening) break;
       
   242 
       
   243       listening.obj.off(name, callback, this);
       
   244     }
       
   245 
       
   246     return this;
       
   247   };
       
   248 
       
   249   // The reducing API that removes a callback from the `events` object.
       
   250   var offApi = function(events, name, callback, options) {
       
   251     if (!events) return;
       
   252 
       
   253     var i = 0, listening;
       
   254     var context = options.context, listeners = options.listeners;
       
   255 
       
   256     // Delete all events listeners and "drop" events.
       
   257     if (!name && !callback && !context) {
       
   258       var ids = _.keys(listeners);
       
   259       for (; i < ids.length; i++) {
       
   260         listening = listeners[ids[i]];
       
   261         delete listeners[listening.id];
       
   262         delete listening.listeningTo[listening.objId];
       
   263       }
       
   264       return;
       
   265     }
       
   266 
       
   267     var names = name ? [name] : _.keys(events);
       
   268     for (; i < names.length; i++) {
       
   269       name = names[i];
       
   270       var handlers = events[name];
       
   271 
       
   272       // Bail out if there are no events stored.
       
   273       if (!handlers) break;
       
   274 
       
   275       // Replace events if there are any remaining.  Otherwise, clean up.
       
   276       var remaining = [];
       
   277       for (var j = 0; j < handlers.length; j++) {
       
   278         var handler = handlers[j];
       
   279         if (
       
   280           callback && callback !== handler.callback &&
       
   281             callback !== handler.callback._callback ||
       
   282               context && context !== handler.context
       
   283         ) {
       
   284           remaining.push(handler);
       
   285         } else {
       
   286           listening = handler.listening;
       
   287           if (listening && --listening.count === 0) {
       
   288             delete listeners[listening.id];
       
   289             delete listening.listeningTo[listening.objId];
       
   290           }
       
   291         }
       
   292       }
       
   293 
       
   294       // Update tail event if the list has any events.  Otherwise, clean up.
       
   295       if (remaining.length) {
       
   296         events[name] = remaining;
       
   297       } else {
       
   298         delete events[name];
       
   299       }
       
   300     }
       
   301     return events;
       
   302   };
       
   303 
       
   304   // Bind an event to only be triggered a single time. After the first time
       
   305   // the callback is invoked, its listener will be removed. If multiple events
       
   306   // are passed in using the space-separated syntax, the handler will fire
       
   307   // once for each event, not once for a combination of all events.
       
   308   Events.once = function(name, callback, context) {
       
   309     // Map the event into a `{event: once}` object.
       
   310     var events = eventsApi(onceMap, {}, name, callback, _.bind(this.off, this));
       
   311     if (typeof name === 'string' && context == null) callback = void 0;
       
   312     return this.on(events, callback, context);
       
   313   };
       
   314 
       
   315   // Inversion-of-control versions of `once`.
       
   316   Events.listenToOnce = function(obj, name, callback) {
       
   317     // Map the event into a `{event: once}` object.
       
   318     var events = eventsApi(onceMap, {}, name, callback, _.bind(this.stopListening, this, obj));
       
   319     return this.listenTo(obj, events);
       
   320   };
       
   321 
       
   322   // Reduces the event callbacks into a map of `{event: onceWrapper}`.
       
   323   // `offer` unbinds the `onceWrapper` after it has been called.
       
   324   var onceMap = function(map, name, callback, offer) {
       
   325     if (callback) {
       
   326       var once = map[name] = _.once(function() {
       
   327         offer(name, once);
       
   328         callback.apply(this, arguments);
       
   329       });
       
   330       once._callback = callback;
       
   331     }
       
   332     return map;
       
   333   };
       
   334 
       
   335   // Trigger one or many events, firing all bound callbacks. Callbacks are
       
   336   // passed the same arguments as `trigger` is, apart from the event name
       
   337   // (unless you're listening on `"all"`, which will cause your callback to
       
   338   // receive the true name of the event as the first argument).
       
   339   Events.trigger = function(name) {
       
   340     if (!this._events) return this;
       
   341 
       
   342     var length = Math.max(0, arguments.length - 1);
       
   343     var args = Array(length);
       
   344     for (var i = 0; i < length; i++) args[i] = arguments[i + 1];
       
   345 
       
   346     eventsApi(triggerApi, this._events, name, void 0, args);
       
   347     return this;
       
   348   };
       
   349 
       
   350   // Handles triggering the appropriate event callbacks.
       
   351   var triggerApi = function(objEvents, name, callback, args) {
       
   352     if (objEvents) {
       
   353       var events = objEvents[name];
       
   354       var allEvents = objEvents.all;
       
   355       if (events && allEvents) allEvents = allEvents.slice();
       
   356       if (events) triggerEvents(events, args);
       
   357       if (allEvents) triggerEvents(allEvents, [name].concat(args));
       
   358     }
       
   359     return objEvents;
       
   360   };
       
   361 
       
   362   // A difficult-to-believe, but optimized internal dispatch function for
       
   363   // triggering events. Tries to keep the usual cases speedy (most internal
       
   364   // Backbone events have 3 arguments).
       
   365   var triggerEvents = function(events, args) {
       
   366     var ev, i = -1, l = events.length, a1 = args[0], a2 = args[1], a3 = args[2];
       
   367     switch (args.length) {
       
   368       case 0: while (++i < l) (ev = events[i]).callback.call(ev.ctx); return;
       
   369       case 1: while (++i < l) (ev = events[i]).callback.call(ev.ctx, a1); return;
       
   370       case 2: while (++i < l) (ev = events[i]).callback.call(ev.ctx, a1, a2); return;
       
   371       case 3: while (++i < l) (ev = events[i]).callback.call(ev.ctx, a1, a2, a3); return;
       
   372       default: while (++i < l) (ev = events[i]).callback.apply(ev.ctx, args); return;
       
   373     }
       
   374   };
       
   375 
       
   376   // Aliases for backwards compatibility.
       
   377   Events.bind   = Events.on;
       
   378   Events.unbind = Events.off;
       
   379 
       
   380   // Allow the `Backbone` object to serve as a global event bus, for folks who
       
   381   // want global "pubsub" in a convenient place.
       
   382   _.extend(Backbone, Events);
       
   383 
       
   384   // Backbone.Model
       
   385   // --------------
       
   386 
       
   387   // Backbone **Models** are the basic data object in the framework --
       
   388   // frequently representing a row in a table in a database on your server.
       
   389   // A discrete chunk of data and a bunch of useful, related methods for
       
   390   // performing computations and transformations on that data.
       
   391 
       
   392   // Create a new model with the specified attributes. A client id (`cid`)
       
   393   // is automatically generated and assigned for you.
       
   394   var Model = Backbone.Model = function(attributes, options) {
       
   395     var attrs = attributes || {};
       
   396     options || (options = {});
       
   397     this.cid = _.uniqueId(this.cidPrefix);
       
   398     this.attributes = {};
       
   399     if (options.collection) this.collection = options.collection;
       
   400     if (options.parse) attrs = this.parse(attrs, options) || {};
       
   401     var defaults = _.result(this, 'defaults');
       
   402     attrs = _.defaults(_.extend({}, defaults, attrs), defaults);
       
   403     this.set(attrs, options);
       
   404     this.changed = {};
       
   405     this.initialize.apply(this, arguments);
       
   406   };
       
   407 
       
   408   // Attach all inheritable methods to the Model prototype.
       
   409   _.extend(Model.prototype, Events, {
       
   410 
       
   411     // A hash of attributes whose current and previous value differ.
       
   412     changed: null,
       
   413 
       
   414     // The value returned during the last failed validation.
       
   415     validationError: null,
       
   416 
       
   417     // The default name for the JSON `id` attribute is `"id"`. MongoDB and
       
   418     // CouchDB users may want to set this to `"_id"`.
       
   419     idAttribute: 'id',
       
   420 
       
   421     // The prefix is used to create the client id which is used to identify models locally.
       
   422     // You may want to override this if you're experiencing name clashes with model ids.
       
   423     cidPrefix: 'c',
       
   424 
       
   425     // Initialize is an empty function by default. Override it with your own
       
   426     // initialization logic.
       
   427     initialize: function(){},
       
   428 
       
   429     // Return a copy of the model's `attributes` object.
       
   430     toJSON: function(options) {
       
   431       return _.clone(this.attributes);
       
   432     },
       
   433 
       
   434     // Proxy `Backbone.sync` by default -- but override this if you need
       
   435     // custom syncing semantics for *this* particular model.
       
   436     sync: function() {
       
   437       return Backbone.sync.apply(this, arguments);
       
   438     },
       
   439 
       
   440     // Get the value of an attribute.
       
   441     get: function(attr) {
       
   442       return this.attributes[attr];
       
   443     },
       
   444 
       
   445     // Get the HTML-escaped value of an attribute.
       
   446     escape: function(attr) {
       
   447       return _.escape(this.get(attr));
       
   448     },
       
   449 
       
   450     // Returns `true` if the attribute contains a value that is not null
       
   451     // or undefined.
       
   452     has: function(attr) {
       
   453       return this.get(attr) != null;
       
   454     },
       
   455 
       
   456     // Special-cased proxy to underscore's `_.matches` method.
       
   457     matches: function(attrs) {
       
   458       return !!_.iteratee(attrs, this)(this.attributes);
       
   459     },
       
   460 
       
   461     // Set a hash of model attributes on the object, firing `"change"`. This is
       
   462     // the core primitive operation of a model, updating the data and notifying
       
   463     // anyone who needs to know about the change in state. The heart of the beast.
       
   464     set: function(key, val, options) {
       
   465       if (key == null) return this;
       
   466 
       
   467       // Handle both `"key", value` and `{key: value}` -style arguments.
       
   468       var attrs;
       
   469       if (typeof key === 'object') {
       
   470         attrs = key;
       
   471         options = val;
       
   472       } else {
       
   473         (attrs = {})[key] = val;
       
   474       }
       
   475 
       
   476       options || (options = {});
       
   477 
       
   478       // Run validation.
       
   479       if (!this._validate(attrs, options)) return false;
       
   480 
       
   481       // Extract attributes and options.
       
   482       var unset      = options.unset;
       
   483       var silent     = options.silent;
       
   484       var changes    = [];
       
   485       var changing   = this._changing;
       
   486       this._changing = true;
       
   487 
       
   488       if (!changing) {
       
   489         this._previousAttributes = _.clone(this.attributes);
       
   490         this.changed = {};
       
   491       }
       
   492 
       
   493       var current = this.attributes;
       
   494       var changed = this.changed;
       
   495       var prev    = this._previousAttributes;
       
   496 
       
   497       // For each `set` attribute, update or delete the current value.
       
   498       for (var attr in attrs) {
       
   499         val = attrs[attr];
       
   500         if (!_.isEqual(current[attr], val)) changes.push(attr);
       
   501         if (!_.isEqual(prev[attr], val)) {
       
   502           changed[attr] = val;
       
   503         } else {
       
   504           delete changed[attr];
       
   505         }
       
   506         unset ? delete current[attr] : current[attr] = val;
       
   507       }
       
   508 
       
   509       // Update the `id`.
       
   510       if (this.idAttribute in attrs) this.id = this.get(this.idAttribute);
       
   511 
       
   512       // Trigger all relevant attribute changes.
       
   513       if (!silent) {
       
   514         if (changes.length) this._pending = options;
       
   515         for (var i = 0; i < changes.length; i++) {
       
   516           this.trigger('change:' + changes[i], this, current[changes[i]], options);
       
   517         }
       
   518       }
       
   519 
       
   520       // You might be wondering why there's a `while` loop here. Changes can
       
   521       // be recursively nested within `"change"` events.
       
   522       if (changing) return this;
       
   523       if (!silent) {
       
   524         while (this._pending) {
       
   525           options = this._pending;
       
   526           this._pending = false;
       
   527           this.trigger('change', this, options);
       
   528         }
       
   529       }
       
   530       this._pending = false;
       
   531       this._changing = false;
       
   532       return this;
       
   533     },
       
   534 
       
   535     // Remove an attribute from the model, firing `"change"`. `unset` is a noop
       
   536     // if the attribute doesn't exist.
       
   537     unset: function(attr, options) {
       
   538       return this.set(attr, void 0, _.extend({}, options, {unset: true}));
       
   539     },
       
   540 
       
   541     // Clear all attributes on the model, firing `"change"`.
       
   542     clear: function(options) {
       
   543       var attrs = {};
       
   544       for (var key in this.attributes) attrs[key] = void 0;
       
   545       return this.set(attrs, _.extend({}, options, {unset: true}));
       
   546     },
       
   547 
       
   548     // Determine if the model has changed since the last `"change"` event.
       
   549     // If you specify an attribute name, determine if that attribute has changed.
       
   550     hasChanged: function(attr) {
       
   551       if (attr == null) return !_.isEmpty(this.changed);
       
   552       return _.has(this.changed, attr);
       
   553     },
       
   554 
       
   555     // Return an object containing all the attributes that have changed, or
       
   556     // false if there are no changed attributes. Useful for determining what
       
   557     // parts of a view need to be updated and/or what attributes need to be
       
   558     // persisted to the server. Unset attributes will be set to undefined.
       
   559     // You can also pass an attributes object to diff against the model,
       
   560     // determining if there *would be* a change.
       
   561     changedAttributes: function(diff) {
       
   562       if (!diff) return this.hasChanged() ? _.clone(this.changed) : false;
       
   563       var old = this._changing ? this._previousAttributes : this.attributes;
       
   564       var changed = {};
       
   565       for (var attr in diff) {
       
   566         var val = diff[attr];
       
   567         if (_.isEqual(old[attr], val)) continue;
       
   568         changed[attr] = val;
       
   569       }
       
   570       return _.size(changed) ? changed : false;
       
   571     },
       
   572 
       
   573     // Get the previous value of an attribute, recorded at the time the last
       
   574     // `"change"` event was fired.
       
   575     previous: function(attr) {
       
   576       if (attr == null || !this._previousAttributes) return null;
       
   577       return this._previousAttributes[attr];
       
   578     },
       
   579 
       
   580     // Get all of the attributes of the model at the time of the previous
       
   581     // `"change"` event.
       
   582     previousAttributes: function() {
       
   583       return _.clone(this._previousAttributes);
       
   584     },
       
   585 
       
   586     // Fetch the model from the server, merging the response with the model's
       
   587     // local attributes. Any changed attributes will trigger a "change" event.
       
   588     fetch: function(options) {
       
   589       options = _.extend({parse: true}, options);
       
   590       var model = this;
       
   591       var success = options.success;
       
   592       options.success = function(resp) {
       
   593         var serverAttrs = options.parse ? model.parse(resp, options) : resp;
       
   594         if (!model.set(serverAttrs, options)) return false;
       
   595         if (success) success.call(options.context, model, resp, options);
       
   596         model.trigger('sync', model, resp, options);
       
   597       };
       
   598       wrapError(this, options);
       
   599       return this.sync('read', this, options);
       
   600     },
       
   601 
       
   602     // Set a hash of model attributes, and sync the model to the server.
       
   603     // If the server returns an attributes hash that differs, the model's
       
   604     // state will be `set` again.
       
   605     save: function(key, val, options) {
       
   606       // Handle both `"key", value` and `{key: value}` -style arguments.
       
   607       var attrs;
       
   608       if (key == null || typeof key === 'object') {
       
   609         attrs = key;
       
   610         options = val;
       
   611       } else {
       
   612         (attrs = {})[key] = val;
       
   613       }
       
   614 
       
   615       options = _.extend({validate: true, parse: true}, options);
       
   616       var wait = options.wait;
       
   617 
       
   618       // If we're not waiting and attributes exist, save acts as
       
   619       // `set(attr).save(null, opts)` with validation. Otherwise, check if
       
   620       // the model will be valid when the attributes, if any, are set.
       
   621       if (attrs && !wait) {
       
   622         if (!this.set(attrs, options)) return false;
       
   623       } else if (!this._validate(attrs, options)) {
       
   624         return false;
       
   625       }
       
   626 
       
   627       // After a successful server-side save, the client is (optionally)
       
   628       // updated with the server-side state.
       
   629       var model = this;
       
   630       var success = options.success;
       
   631       var attributes = this.attributes;
       
   632       options.success = function(resp) {
       
   633         // Ensure attributes are restored during synchronous saves.
       
   634         model.attributes = attributes;
       
   635         var serverAttrs = options.parse ? model.parse(resp, options) : resp;
       
   636         if (wait) serverAttrs = _.extend({}, attrs, serverAttrs);
       
   637         if (serverAttrs && !model.set(serverAttrs, options)) return false;
       
   638         if (success) success.call(options.context, model, resp, options);
       
   639         model.trigger('sync', model, resp, options);
       
   640       };
       
   641       wrapError(this, options);
       
   642 
       
   643       // Set temporary attributes if `{wait: true}` to properly find new ids.
       
   644       if (attrs && wait) this.attributes = _.extend({}, attributes, attrs);
       
   645 
       
   646       var method = this.isNew() ? 'create' : (options.patch ? 'patch' : 'update');
       
   647       if (method === 'patch' && !options.attrs) options.attrs = attrs;
       
   648       var xhr = this.sync(method, this, options);
       
   649 
       
   650       // Restore attributes.
       
   651       this.attributes = attributes;
       
   652 
       
   653       return xhr;
       
   654     },
       
   655 
       
   656     // Destroy this model on the server if it was already persisted.
       
   657     // Optimistically removes the model from its collection, if it has one.
       
   658     // If `wait: true` is passed, waits for the server to respond before removal.
       
   659     destroy: function(options) {
       
   660       options = options ? _.clone(options) : {};
       
   661       var model = this;
       
   662       var success = options.success;
       
   663       var wait = options.wait;
       
   664 
       
   665       var destroy = function() {
       
   666         model.stopListening();
       
   667         model.trigger('destroy', model, model.collection, options);
       
   668       };
       
   669 
       
   670       options.success = function(resp) {
       
   671         if (wait) destroy();
       
   672         if (success) success.call(options.context, model, resp, options);
       
   673         if (!model.isNew()) model.trigger('sync', model, resp, options);
       
   674       };
       
   675 
       
   676       var xhr = false;
       
   677       if (this.isNew()) {
       
   678         _.defer(options.success);
       
   679       } else {
       
   680         wrapError(this, options);
       
   681         xhr = this.sync('delete', this, options);
       
   682       }
       
   683       if (!wait) destroy();
       
   684       return xhr;
       
   685     },
       
   686 
       
   687     // Default URL for the model's representation on the server -- if you're
       
   688     // using Backbone's restful methods, override this to change the endpoint
       
   689     // that will be called.
       
   690     url: function() {
       
   691       var base =
       
   692         _.result(this, 'urlRoot') ||
       
   693         _.result(this.collection, 'url') ||
       
   694         urlError();
       
   695       if (this.isNew()) return base;
       
   696       var id = this.get(this.idAttribute);
       
   697       return base.replace(/[^\/]$/, '$&/') + encodeURIComponent(id);
       
   698     },
       
   699 
       
   700     // **parse** converts a response into the hash of attributes to be `set` on
       
   701     // the model. The default implementation is just to pass the response along.
       
   702     parse: function(resp, options) {
       
   703       return resp;
       
   704     },
       
   705 
       
   706     // Create a new model with identical attributes to this one.
       
   707     clone: function() {
       
   708       return new this.constructor(this.attributes);
       
   709     },
       
   710 
       
   711     // A model is new if it has never been saved to the server, and lacks an id.
       
   712     isNew: function() {
       
   713       return !this.has(this.idAttribute);
       
   714     },
       
   715 
       
   716     // Check if the model is currently in a valid state.
       
   717     isValid: function(options) {
       
   718       return this._validate({}, _.extend({}, options, {validate: true}));
       
   719     },
       
   720 
       
   721     // Run validation against the next complete set of model attributes,
       
   722     // returning `true` if all is well. Otherwise, fire an `"invalid"` event.
       
   723     _validate: function(attrs, options) {
       
   724       if (!options.validate || !this.validate) return true;
       
   725       attrs = _.extend({}, this.attributes, attrs);
       
   726       var error = this.validationError = this.validate(attrs, options) || null;
       
   727       if (!error) return true;
       
   728       this.trigger('invalid', this, error, _.extend(options, {validationError: error}));
       
   729       return false;
       
   730     }
       
   731 
       
   732   });
       
   733 
       
   734   // Underscore methods that we want to implement on the Model, mapped to the
       
   735   // number of arguments they take.
       
   736   var modelMethods = {keys: 1, values: 1, pairs: 1, invert: 1, pick: 0,
       
   737       omit: 0, chain: 1, isEmpty: 1};
       
   738 
       
   739   // Mix in each Underscore method as a proxy to `Model#attributes`.
       
   740   addUnderscoreMethods(Model, modelMethods, 'attributes');
       
   741 
       
   742   // Backbone.Collection
       
   743   // -------------------
       
   744 
       
   745   // If models tend to represent a single row of data, a Backbone Collection is
       
   746   // more analogous to a table full of data ... or a small slice or page of that
       
   747   // table, or a collection of rows that belong together for a particular reason
       
   748   // -- all of the messages in this particular folder, all of the documents
       
   749   // belonging to this particular author, and so on. Collections maintain
       
   750   // indexes of their models, both in order, and for lookup by `id`.
       
   751 
       
   752   // Create a new **Collection**, perhaps to contain a specific type of `model`.
       
   753   // If a `comparator` is specified, the Collection will maintain
       
   754   // its models in sort order, as they're added and removed.
       
   755   var Collection = Backbone.Collection = function(models, options) {
       
   756     options || (options = {});
       
   757     if (options.model) this.model = options.model;
       
   758     if (options.comparator !== void 0) this.comparator = options.comparator;
       
   759     this._reset();
       
   760     this.initialize.apply(this, arguments);
       
   761     if (models) this.reset(models, _.extend({silent: true}, options));
       
   762   };
       
   763 
       
   764   // Default options for `Collection#set`.
       
   765   var setOptions = {add: true, remove: true, merge: true};
       
   766   var addOptions = {add: true, remove: false};
       
   767 
       
   768   // Splices `insert` into `array` at index `at`.
       
   769   var splice = function(array, insert, at) {
       
   770     at = Math.min(Math.max(at, 0), array.length);
       
   771     var tail = Array(array.length - at);
       
   772     var length = insert.length;
       
   773     var i;
       
   774     for (i = 0; i < tail.length; i++) tail[i] = array[i + at];
       
   775     for (i = 0; i < length; i++) array[i + at] = insert[i];
       
   776     for (i = 0; i < tail.length; i++) array[i + length + at] = tail[i];
       
   777   };
       
   778 
       
   779   // Define the Collection's inheritable methods.
       
   780   _.extend(Collection.prototype, Events, {
       
   781 
       
   782     // The default model for a collection is just a **Backbone.Model**.
       
   783     // This should be overridden in most cases.
       
   784     model: Model,
       
   785 
       
   786     // Initialize is an empty function by default. Override it with your own
       
   787     // initialization logic.
       
   788     initialize: function(){},
       
   789 
       
   790     // The JSON representation of a Collection is an array of the
       
   791     // models' attributes.
       
   792     toJSON: function(options) {
       
   793       return this.map(function(model) { return model.toJSON(options); });
       
   794     },
       
   795 
       
   796     // Proxy `Backbone.sync` by default.
       
   797     sync: function() {
       
   798       return Backbone.sync.apply(this, arguments);
       
   799     },
       
   800 
       
   801     // Add a model, or list of models to the set. `models` may be Backbone
       
   802     // Models or raw JavaScript objects to be converted to Models, or any
       
   803     // combination of the two.
       
   804     add: function(models, options) {
       
   805       return this.set(models, _.extend({merge: false}, options, addOptions));
       
   806     },
       
   807 
       
   808     // Remove a model, or a list of models from the set.
       
   809     remove: function(models, options) {
       
   810       options = _.extend({}, options);
       
   811       var singular = !_.isArray(models);
       
   812       models = singular ? [models] : models.slice();
       
   813       var removed = this._removeModels(models, options);
       
   814       if (!options.silent && removed.length) {
       
   815         options.changes = {added: [], merged: [], removed: removed};
       
   816         this.trigger('update', this, options);
       
   817       }
       
   818       return singular ? removed[0] : removed;
       
   819     },
       
   820 
       
   821     // Update a collection by `set`-ing a new list of models, adding new ones,
       
   822     // removing models that are no longer present, and merging models that
       
   823     // already exist in the collection, as necessary. Similar to **Model#set**,
       
   824     // the core operation for updating the data contained by the collection.
       
   825     set: function(models, options) {
       
   826       if (models == null) return;
       
   827 
       
   828       options = _.extend({}, setOptions, options);
       
   829       if (options.parse && !this._isModel(models)) {
       
   830         models = this.parse(models, options) || [];
       
   831       }
       
   832 
       
   833       var singular = !_.isArray(models);
       
   834       models = singular ? [models] : models.slice();
       
   835 
       
   836       var at = options.at;
       
   837       if (at != null) at = +at;
       
   838       if (at > this.length) at = this.length;
       
   839       if (at < 0) at += this.length + 1;
       
   840 
       
   841       var set = [];
       
   842       var toAdd = [];
       
   843       var toMerge = [];
       
   844       var toRemove = [];
       
   845       var modelMap = {};
       
   846 
       
   847       var add = options.add;
       
   848       var merge = options.merge;
       
   849       var remove = options.remove;
       
   850 
       
   851       var sort = false;
       
   852       var sortable = this.comparator && at == null && options.sort !== false;
       
   853       var sortAttr = _.isString(this.comparator) ? this.comparator : null;
       
   854 
       
   855       // Turn bare objects into model references, and prevent invalid models
       
   856       // from being added.
       
   857       var model, i;
       
   858       for (i = 0; i < models.length; i++) {
       
   859         model = models[i];
       
   860 
       
   861         // If a duplicate is found, prevent it from being added and
       
   862         // optionally merge it into the existing model.
       
   863         var existing = this.get(model);
       
   864         if (existing) {
       
   865           if (merge && model !== existing) {
       
   866             var attrs = this._isModel(model) ? model.attributes : model;
       
   867             if (options.parse) attrs = existing.parse(attrs, options);
       
   868             existing.set(attrs, options);
       
   869             toMerge.push(existing);
       
   870             if (sortable && !sort) sort = existing.hasChanged(sortAttr);
       
   871           }
       
   872           if (!modelMap[existing.cid]) {
       
   873             modelMap[existing.cid] = true;
       
   874             set.push(existing);
       
   875           }
       
   876           models[i] = existing;
       
   877 
       
   878         // If this is a new, valid model, push it to the `toAdd` list.
       
   879         } else if (add) {
       
   880           model = models[i] = this._prepareModel(model, options);
       
   881           if (model) {
       
   882             toAdd.push(model);
       
   883             this._addReference(model, options);
       
   884             modelMap[model.cid] = true;
       
   885             set.push(model);
       
   886           }
       
   887         }
       
   888       }
       
   889 
       
   890       // Remove stale models.
       
   891       if (remove) {
       
   892         for (i = 0; i < this.length; i++) {
       
   893           model = this.models[i];
       
   894           if (!modelMap[model.cid]) toRemove.push(model);
       
   895         }
       
   896         if (toRemove.length) this._removeModels(toRemove, options);
       
   897       }
       
   898 
       
   899       // See if sorting is needed, update `length` and splice in new models.
       
   900       var orderChanged = false;
       
   901       var replace = !sortable && add && remove;
       
   902       if (set.length && replace) {
       
   903         orderChanged = this.length !== set.length || _.some(this.models, function(m, index) {
       
   904           return m !== set[index];
       
   905         });
       
   906         this.models.length = 0;
       
   907         splice(this.models, set, 0);
       
   908         this.length = this.models.length;
       
   909       } else if (toAdd.length) {
       
   910         if (sortable) sort = true;
       
   911         splice(this.models, toAdd, at == null ? this.length : at);
       
   912         this.length = this.models.length;
       
   913       }
       
   914 
       
   915       // Silently sort the collection if appropriate.
       
   916       if (sort) this.sort({silent: true});
       
   917 
       
   918       // Unless silenced, it's time to fire all appropriate add/sort/update events.
       
   919       if (!options.silent) {
       
   920         for (i = 0; i < toAdd.length; i++) {
       
   921           if (at != null) options.index = at + i;
       
   922           model = toAdd[i];
       
   923           model.trigger('add', model, this, options);
       
   924         }
       
   925         if (sort || orderChanged) this.trigger('sort', this, options);
       
   926         if (toAdd.length || toRemove.length || toMerge.length) {
       
   927           options.changes = {
       
   928             added: toAdd,
       
   929             removed: toRemove,
       
   930             merged: toMerge
       
   931           };
       
   932           this.trigger('update', this, options);
       
   933         }
       
   934       }
       
   935 
       
   936       // Return the added (or merged) model (or models).
       
   937       return singular ? models[0] : models;
       
   938     },
       
   939 
       
   940     // When you have more items than you want to add or remove individually,
       
   941     // you can reset the entire set with a new list of models, without firing
       
   942     // any granular `add` or `remove` events. Fires `reset` when finished.
       
   943     // Useful for bulk operations and optimizations.
       
   944     reset: function(models, options) {
       
   945       options = options ? _.clone(options) : {};
       
   946       for (var i = 0; i < this.models.length; i++) {
       
   947         this._removeReference(this.models[i], options);
       
   948       }
       
   949       options.previousModels = this.models;
       
   950       this._reset();
       
   951       models = this.add(models, _.extend({silent: true}, options));
       
   952       if (!options.silent) this.trigger('reset', this, options);
       
   953       return models;
       
   954     },
       
   955 
       
   956     // Add a model to the end of the collection.
       
   957     push: function(model, options) {
       
   958       return this.add(model, _.extend({at: this.length}, options));
       
   959     },
       
   960 
       
   961     // Remove a model from the end of the collection.
       
   962     pop: function(options) {
       
   963       var model = this.at(this.length - 1);
       
   964       return this.remove(model, options);
       
   965     },
       
   966 
       
   967     // Add a model to the beginning of the collection.
       
   968     unshift: function(model, options) {
       
   969       return this.add(model, _.extend({at: 0}, options));
       
   970     },
       
   971 
       
   972     // Remove a model from the beginning of the collection.
       
   973     shift: function(options) {
       
   974       var model = this.at(0);
       
   975       return this.remove(model, options);
       
   976     },
       
   977 
       
   978     // Slice out a sub-array of models from the collection.
       
   979     slice: function() {
       
   980       return slice.apply(this.models, arguments);
       
   981     },
       
   982 
       
   983     // Get a model from the set by id, cid, model object with id or cid
       
   984     // properties, or an attributes object that is transformed through modelId.
       
   985     get: function(obj) {
       
   986       if (obj == null) return void 0;
       
   987       return this._byId[obj] ||
       
   988         this._byId[this.modelId(obj.attributes || obj)] ||
       
   989         obj.cid && this._byId[obj.cid];
       
   990     },
       
   991 
       
   992     // Returns `true` if the model is in the collection.
       
   993     has: function(obj) {
       
   994       return this.get(obj) != null;
       
   995     },
       
   996 
       
   997     // Get the model at the given index.
       
   998     at: function(index) {
       
   999       if (index < 0) index += this.length;
       
  1000       return this.models[index];
       
  1001     },
       
  1002 
       
  1003     // Return models with matching attributes. Useful for simple cases of
       
  1004     // `filter`.
       
  1005     where: function(attrs, first) {
       
  1006       return this[first ? 'find' : 'filter'](attrs);
       
  1007     },
       
  1008 
       
  1009     // Return the first model with matching attributes. Useful for simple cases
       
  1010     // of `find`.
       
  1011     findWhere: function(attrs) {
       
  1012       return this.where(attrs, true);
       
  1013     },
       
  1014 
       
  1015     // Force the collection to re-sort itself. You don't need to call this under
       
  1016     // normal circumstances, as the set will maintain sort order as each item
       
  1017     // is added.
       
  1018     sort: function(options) {
       
  1019       var comparator = this.comparator;
       
  1020       if (!comparator) throw new Error('Cannot sort a set without a comparator');
       
  1021       options || (options = {});
       
  1022 
       
  1023       var length = comparator.length;
       
  1024       if (_.isFunction(comparator)) comparator = _.bind(comparator, this);
       
  1025 
       
  1026       // Run sort based on type of `comparator`.
       
  1027       if (length === 1 || _.isString(comparator)) {
       
  1028         this.models = this.sortBy(comparator);
       
  1029       } else {
       
  1030         this.models.sort(comparator);
       
  1031       }
       
  1032       if (!options.silent) this.trigger('sort', this, options);
       
  1033       return this;
       
  1034     },
       
  1035 
       
  1036     // Pluck an attribute from each model in the collection.
       
  1037     pluck: function(attr) {
       
  1038       return this.map(attr + '');
       
  1039     },
       
  1040 
       
  1041     // Fetch the default set of models for this collection, resetting the
       
  1042     // collection when they arrive. If `reset: true` is passed, the response
       
  1043     // data will be passed through the `reset` method instead of `set`.
       
  1044     fetch: function(options) {
       
  1045       options = _.extend({parse: true}, options);
       
  1046       var success = options.success;
       
  1047       var collection = this;
       
  1048       options.success = function(resp) {
       
  1049         var method = options.reset ? 'reset' : 'set';
       
  1050         collection[method](resp, options);
       
  1051         if (success) success.call(options.context, collection, resp, options);
       
  1052         collection.trigger('sync', collection, resp, options);
       
  1053       };
       
  1054       wrapError(this, options);
       
  1055       return this.sync('read', this, options);
       
  1056     },
       
  1057 
       
  1058     // Create a new instance of a model in this collection. Add the model to the
       
  1059     // collection immediately, unless `wait: true` is passed, in which case we
       
  1060     // wait for the server to agree.
       
  1061     create: function(model, options) {
       
  1062       options = options ? _.clone(options) : {};
       
  1063       var wait = options.wait;
       
  1064       model = this._prepareModel(model, options);
       
  1065       if (!model) return false;
       
  1066       if (!wait) this.add(model, options);
       
  1067       var collection = this;
       
  1068       var success = options.success;
       
  1069       options.success = function(m, resp, callbackOpts) {
       
  1070         if (wait) collection.add(m, callbackOpts);
       
  1071         if (success) success.call(callbackOpts.context, m, resp, callbackOpts);
       
  1072       };
       
  1073       model.save(null, options);
       
  1074       return model;
       
  1075     },
       
  1076 
       
  1077     // **parse** converts a response into a list of models to be added to the
       
  1078     // collection. The default implementation is just to pass it through.
       
  1079     parse: function(resp, options) {
       
  1080       return resp;
       
  1081     },
       
  1082 
       
  1083     // Create a new collection with an identical list of models as this one.
       
  1084     clone: function() {
       
  1085       return new this.constructor(this.models, {
       
  1086         model: this.model,
       
  1087         comparator: this.comparator
       
  1088       });
       
  1089     },
       
  1090 
       
  1091     // Define how to uniquely identify models in the collection.
       
  1092     modelId: function(attrs) {
       
  1093       return attrs[this.model.prototype.idAttribute || 'id'];
       
  1094     },
       
  1095 
       
  1096     // Private method to reset all internal state. Called when the collection
       
  1097     // is first initialized or reset.
       
  1098     _reset: function() {
       
  1099       this.length = 0;
       
  1100       this.models = [];
       
  1101       this._byId  = {};
       
  1102     },
       
  1103 
       
  1104     // Prepare a hash of attributes (or other model) to be added to this
       
  1105     // collection.
       
  1106     _prepareModel: function(attrs, options) {
       
  1107       if (this._isModel(attrs)) {
       
  1108         if (!attrs.collection) attrs.collection = this;
       
  1109         return attrs;
       
  1110       }
       
  1111       options = options ? _.clone(options) : {};
       
  1112       options.collection = this;
       
  1113       var model = new this.model(attrs, options);
       
  1114       if (!model.validationError) return model;
       
  1115       this.trigger('invalid', this, model.validationError, options);
       
  1116       return false;
       
  1117     },
       
  1118 
       
  1119     // Internal method called by both remove and set.
       
  1120     _removeModels: function(models, options) {
       
  1121       var removed = [];
       
  1122       for (var i = 0; i < models.length; i++) {
       
  1123         var model = this.get(models[i]);
       
  1124         if (!model) continue;
       
  1125 
       
  1126         var index = this.indexOf(model);
       
  1127         this.models.splice(index, 1);
       
  1128         this.length--;
       
  1129 
       
  1130         // Remove references before triggering 'remove' event to prevent an
       
  1131         // infinite loop. #3693
       
  1132         delete this._byId[model.cid];
       
  1133         var id = this.modelId(model.attributes);
       
  1134         if (id != null) delete this._byId[id];
       
  1135 
       
  1136         if (!options.silent) {
       
  1137           options.index = index;
       
  1138           model.trigger('remove', model, this, options);
       
  1139         }
       
  1140 
       
  1141         removed.push(model);
       
  1142         this._removeReference(model, options);
       
  1143       }
       
  1144       return removed;
       
  1145     },
       
  1146 
       
  1147     // Method for checking whether an object should be considered a model for
       
  1148     // the purposes of adding to the collection.
       
  1149     _isModel: function(model) {
       
  1150       return model instanceof Model;
       
  1151     },
       
  1152 
       
  1153     // Internal method to create a model's ties to a collection.
       
  1154     _addReference: function(model, options) {
       
  1155       this._byId[model.cid] = model;
       
  1156       var id = this.modelId(model.attributes);
       
  1157       if (id != null) this._byId[id] = model;
       
  1158       model.on('all', this._onModelEvent, this);
       
  1159     },
       
  1160 
       
  1161     // Internal method to sever a model's ties to a collection.
       
  1162     _removeReference: function(model, options) {
       
  1163       delete this._byId[model.cid];
       
  1164       var id = this.modelId(model.attributes);
       
  1165       if (id != null) delete this._byId[id];
       
  1166       if (this === model.collection) delete model.collection;
       
  1167       model.off('all', this._onModelEvent, this);
       
  1168     },
       
  1169 
       
  1170     // Internal method called every time a model in the set fires an event.
       
  1171     // Sets need to update their indexes when models change ids. All other
       
  1172     // events simply proxy through. "add" and "remove" events that originate
       
  1173     // in other collections are ignored.
       
  1174     _onModelEvent: function(event, model, collection, options) {
       
  1175       if (model) {
       
  1176         if ((event === 'add' || event === 'remove') && collection !== this) return;
       
  1177         if (event === 'destroy') this.remove(model, options);
       
  1178         if (event === 'change') {
       
  1179           var prevId = this.modelId(model.previousAttributes());
       
  1180           var id = this.modelId(model.attributes);
       
  1181           if (prevId !== id) {
       
  1182             if (prevId != null) delete this._byId[prevId];
       
  1183             if (id != null) this._byId[id] = model;
       
  1184           }
       
  1185         }
       
  1186       }
       
  1187       this.trigger.apply(this, arguments);
       
  1188     }
       
  1189 
       
  1190   });
       
  1191 
       
  1192   // Underscore methods that we want to implement on the Collection.
       
  1193   // 90% of the core usefulness of Backbone Collections is actually implemented
       
  1194   // right here:
       
  1195   var collectionMethods = {forEach: 3, each: 3, map: 3, collect: 3, reduce: 0,
       
  1196       foldl: 0, inject: 0, reduceRight: 0, foldr: 0, find: 3, detect: 3, filter: 3,
       
  1197       select: 3, reject: 3, every: 3, all: 3, some: 3, any: 3, include: 3, includes: 3,
       
  1198       contains: 3, invoke: 0, max: 3, min: 3, toArray: 1, size: 1, first: 3,
       
  1199       head: 3, take: 3, initial: 3, rest: 3, tail: 3, drop: 3, last: 3,
       
  1200       without: 0, difference: 0, indexOf: 3, shuffle: 1, lastIndexOf: 3,
       
  1201       isEmpty: 1, chain: 1, sample: 3, partition: 3, groupBy: 3, countBy: 3,
       
  1202       sortBy: 3, indexBy: 3, findIndex: 3, findLastIndex: 3};
       
  1203 
       
  1204   // Mix in each Underscore method as a proxy to `Collection#models`.
       
  1205   addUnderscoreMethods(Collection, collectionMethods, 'models');
       
  1206 
       
  1207   // Backbone.View
       
  1208   // -------------
       
  1209 
       
  1210   // Backbone Views are almost more convention than they are actual code. A View
       
  1211   // is simply a JavaScript object that represents a logical chunk of UI in the
       
  1212   // DOM. This might be a single item, an entire list, a sidebar or panel, or
       
  1213   // even the surrounding frame which wraps your whole app. Defining a chunk of
       
  1214   // UI as a **View** allows you to define your DOM events declaratively, without
       
  1215   // having to worry about render order ... and makes it easy for the view to
       
  1216   // react to specific changes in the state of your models.
       
  1217 
       
  1218   // Creating a Backbone.View creates its initial element outside of the DOM,
       
  1219   // if an existing element is not provided...
       
  1220   var View = Backbone.View = function(options) {
       
  1221     this.cid = _.uniqueId('view');
       
  1222     _.extend(this, _.pick(options, viewOptions));
       
  1223     this._ensureElement();
       
  1224     this.initialize.apply(this, arguments);
       
  1225   };
       
  1226 
       
  1227   // Cached regex to split keys for `delegate`.
       
  1228   var delegateEventSplitter = /^(\S+)\s*(.*)$/;
       
  1229 
       
  1230   // List of view options to be set as properties.
       
  1231   var viewOptions = ['model', 'collection', 'el', 'id', 'attributes', 'className', 'tagName', 'events'];
       
  1232 
       
  1233   // Set up all inheritable **Backbone.View** properties and methods.
       
  1234   _.extend(View.prototype, Events, {
       
  1235 
       
  1236     // The default `tagName` of a View's element is `"div"`.
       
  1237     tagName: 'div',
       
  1238 
       
  1239     // jQuery delegate for element lookup, scoped to DOM elements within the
       
  1240     // current view. This should be preferred to global lookups where possible.
       
  1241     $: function(selector) {
       
  1242       return this.$el.find(selector);
       
  1243     },
       
  1244 
       
  1245     // Initialize is an empty function by default. Override it with your own
       
  1246     // initialization logic.
       
  1247     initialize: function(){},
       
  1248 
       
  1249     // **render** is the core function that your view should override, in order
       
  1250     // to populate its element (`this.el`), with the appropriate HTML. The
       
  1251     // convention is for **render** to always return `this`.
       
  1252     render: function() {
       
  1253       return this;
       
  1254     },
       
  1255 
       
  1256     // Remove this view by taking the element out of the DOM, and removing any
       
  1257     // applicable Backbone.Events listeners.
       
  1258     remove: function() {
       
  1259       this._removeElement();
       
  1260       this.stopListening();
       
  1261       return this;
       
  1262     },
       
  1263 
       
  1264     // Remove this view's element from the document and all event listeners
       
  1265     // attached to it. Exposed for subclasses using an alternative DOM
       
  1266     // manipulation API.
       
  1267     _removeElement: function() {
       
  1268       this.$el.remove();
       
  1269     },
       
  1270 
       
  1271     // Change the view's element (`this.el` property) and re-delegate the
       
  1272     // view's events on the new element.
       
  1273     setElement: function(element) {
       
  1274       this.undelegateEvents();
       
  1275       this._setElement(element);
       
  1276       this.delegateEvents();
       
  1277       return this;
       
  1278     },
       
  1279 
       
  1280     // Creates the `this.el` and `this.$el` references for this view using the
       
  1281     // given `el`. `el` can be a CSS selector or an HTML string, a jQuery
       
  1282     // context or an element. Subclasses can override this to utilize an
       
  1283     // alternative DOM manipulation API and are only required to set the
       
  1284     // `this.el` property.
       
  1285     _setElement: function(el) {
       
  1286       this.$el = el instanceof Backbone.$ ? el : Backbone.$(el);
       
  1287       this.el = this.$el[0];
       
  1288     },
       
  1289 
       
  1290     // Set callbacks, where `this.events` is a hash of
       
  1291     //
       
  1292     // *{"event selector": "callback"}*
       
  1293     //
       
  1294     //     {
       
  1295     //       'mousedown .title':  'edit',
       
  1296     //       'click .button':     'save',
       
  1297     //       'click .open':       function(e) { ... }
       
  1298     //     }
       
  1299     //
       
  1300     // pairs. Callbacks will be bound to the view, with `this` set properly.
       
  1301     // Uses event delegation for efficiency.
       
  1302     // Omitting the selector binds the event to `this.el`.
       
  1303     delegateEvents: function(events) {
       
  1304       events || (events = _.result(this, 'events'));
       
  1305       if (!events) return this;
       
  1306       this.undelegateEvents();
       
  1307       for (var key in events) {
       
  1308         var method = events[key];
       
  1309         if (!_.isFunction(method)) method = this[method];
       
  1310         if (!method) continue;
       
  1311         var match = key.match(delegateEventSplitter);
       
  1312         this.delegate(match[1], match[2], _.bind(method, this));
       
  1313       }
       
  1314       return this;
       
  1315     },
       
  1316 
       
  1317     // Add a single event listener to the view's element (or a child element
       
  1318     // using `selector`). This only works for delegate-able events: not `focus`,
       
  1319     // `blur`, and not `change`, `submit`, and `reset` in Internet Explorer.
       
  1320     delegate: function(eventName, selector, listener) {
       
  1321       this.$el.on(eventName + '.delegateEvents' + this.cid, selector, listener);
       
  1322       return this;
       
  1323     },
       
  1324 
       
  1325     // Clears all callbacks previously bound to the view by `delegateEvents`.
       
  1326     // You usually don't need to use this, but may wish to if you have multiple
       
  1327     // Backbone views attached to the same DOM element.
       
  1328     undelegateEvents: function() {
       
  1329       if (this.$el) this.$el.off('.delegateEvents' + this.cid);
       
  1330       return this;
       
  1331     },
       
  1332 
       
  1333     // A finer-grained `undelegateEvents` for removing a single delegated event.
       
  1334     // `selector` and `listener` are both optional.
       
  1335     undelegate: function(eventName, selector, listener) {
       
  1336       this.$el.off(eventName + '.delegateEvents' + this.cid, selector, listener);
       
  1337       return this;
       
  1338     },
       
  1339 
       
  1340     // Produces a DOM element to be assigned to your view. Exposed for
       
  1341     // subclasses using an alternative DOM manipulation API.
       
  1342     _createElement: function(tagName) {
       
  1343       return document.createElement(tagName);
       
  1344     },
       
  1345 
       
  1346     // Ensure that the View has a DOM element to render into.
       
  1347     // If `this.el` is a string, pass it through `$()`, take the first
       
  1348     // matching element, and re-assign it to `el`. Otherwise, create
       
  1349     // an element from the `id`, `className` and `tagName` properties.
       
  1350     _ensureElement: function() {
       
  1351       if (!this.el) {
       
  1352         var attrs = _.extend({}, _.result(this, 'attributes'));
       
  1353         if (this.id) attrs.id = _.result(this, 'id');
       
  1354         if (this.className) attrs['class'] = _.result(this, 'className');
       
  1355         this.setElement(this._createElement(_.result(this, 'tagName')));
       
  1356         this._setAttributes(attrs);
       
  1357       } else {
       
  1358         this.setElement(_.result(this, 'el'));
       
  1359       }
       
  1360     },
       
  1361 
       
  1362     // Set attributes from a hash on this view's element.  Exposed for
       
  1363     // subclasses using an alternative DOM manipulation API.
       
  1364     _setAttributes: function(attributes) {
       
  1365       this.$el.attr(attributes);
       
  1366     }
       
  1367 
       
  1368   });
       
  1369 
       
  1370   // Backbone.sync
       
  1371   // -------------
       
  1372 
       
  1373   // Override this function to change the manner in which Backbone persists
       
  1374   // models to the server. You will be passed the type of request, and the
       
  1375   // model in question. By default, makes a RESTful Ajax request
       
  1376   // to the model's `url()`. Some possible customizations could be:
       
  1377   //
       
  1378   // * Use `setTimeout` to batch rapid-fire updates into a single request.
       
  1379   // * Send up the models as XML instead of JSON.
       
  1380   // * Persist models via WebSockets instead of Ajax.
       
  1381   //
       
  1382   // Turn on `Backbone.emulateHTTP` in order to send `PUT` and `DELETE` requests
       
  1383   // as `POST`, with a `_method` parameter containing the true HTTP method,
       
  1384   // as well as all requests with the body as `application/x-www-form-urlencoded`
       
  1385   // instead of `application/json` with the model in a param named `model`.
       
  1386   // Useful when interfacing with server-side languages like **PHP** that make
       
  1387   // it difficult to read the body of `PUT` requests.
       
  1388   Backbone.sync = function(method, model, options) {
       
  1389     var type = methodMap[method];
       
  1390 
       
  1391     // Default options, unless specified.
       
  1392     _.defaults(options || (options = {}), {
       
  1393       emulateHTTP: Backbone.emulateHTTP,
       
  1394       emulateJSON: Backbone.emulateJSON
       
  1395     });
       
  1396 
       
  1397     // Default JSON-request options.
       
  1398     var params = {type: type, dataType: 'json'};
       
  1399 
       
  1400     // Ensure that we have a URL.
       
  1401     if (!options.url) {
       
  1402       params.url = _.result(model, 'url') || urlError();
       
  1403     }
       
  1404 
       
  1405     // Ensure that we have the appropriate request data.
       
  1406     if (options.data == null && model && (method === 'create' || method === 'update' || method === 'patch')) {
       
  1407       params.contentType = 'application/json';
       
  1408       params.data = JSON.stringify(options.attrs || model.toJSON(options));
       
  1409     }
       
  1410 
       
  1411     // For older servers, emulate JSON by encoding the request into an HTML-form.
       
  1412     if (options.emulateJSON) {
       
  1413       params.contentType = 'application/x-www-form-urlencoded';
       
  1414       params.data = params.data ? {model: params.data} : {};
       
  1415     }
       
  1416 
       
  1417     // For older servers, emulate HTTP by mimicking the HTTP method with `_method`
       
  1418     // And an `X-HTTP-Method-Override` header.
       
  1419     if (options.emulateHTTP && (type === 'PUT' || type === 'DELETE' || type === 'PATCH')) {
       
  1420       params.type = 'POST';
       
  1421       if (options.emulateJSON) params.data._method = type;
       
  1422       var beforeSend = options.beforeSend;
       
  1423       options.beforeSend = function(xhr) {
       
  1424         xhr.setRequestHeader('X-HTTP-Method-Override', type);
       
  1425         if (beforeSend) return beforeSend.apply(this, arguments);
       
  1426       };
       
  1427     }
       
  1428 
       
  1429     // Don't process data on a non-GET request.
       
  1430     if (params.type !== 'GET' && !options.emulateJSON) {
       
  1431       params.processData = false;
       
  1432     }
       
  1433 
       
  1434     // Pass along `textStatus` and `errorThrown` from jQuery.
       
  1435     var error = options.error;
       
  1436     options.error = function(xhr, textStatus, errorThrown) {
       
  1437       options.textStatus = textStatus;
       
  1438       options.errorThrown = errorThrown;
       
  1439       if (error) error.call(options.context, xhr, textStatus, errorThrown);
       
  1440     };
       
  1441 
       
  1442     // Make the request, allowing the user to override any Ajax options.
       
  1443     var xhr = options.xhr = Backbone.ajax(_.extend(params, options));
       
  1444     model.trigger('request', model, xhr, options);
       
  1445     return xhr;
       
  1446   };
       
  1447 
       
  1448   // Map from CRUD to HTTP for our default `Backbone.sync` implementation.
       
  1449   var methodMap = {
       
  1450     'create': 'POST',
       
  1451     'update': 'PUT',
       
  1452     'patch': 'PATCH',
       
  1453     'delete': 'DELETE',
       
  1454     'read': 'GET'
       
  1455   };
       
  1456 
       
  1457   // Set the default implementation of `Backbone.ajax` to proxy through to `$`.
       
  1458   // Override this if you'd like to use a different library.
       
  1459   Backbone.ajax = function() {
       
  1460     return Backbone.$.ajax.apply(Backbone.$, arguments);
       
  1461   };
       
  1462 
       
  1463   // Backbone.Router
       
  1464   // ---------------
       
  1465 
       
  1466   // Routers map faux-URLs to actions, and fire events when routes are
       
  1467   // matched. Creating a new one sets its `routes` hash, if not set statically.
       
  1468   var Router = Backbone.Router = function(options) {
       
  1469     options || (options = {});
       
  1470     if (options.routes) this.routes = options.routes;
       
  1471     this._bindRoutes();
       
  1472     this.initialize.apply(this, arguments);
       
  1473   };
       
  1474 
       
  1475   // Cached regular expressions for matching named param parts and splatted
       
  1476   // parts of route strings.
       
  1477   var optionalParam = /\((.*?)\)/g;
       
  1478   var namedParam    = /(\(\?)?:\w+/g;
       
  1479   var splatParam    = /\*\w+/g;
       
  1480   var escapeRegExp  = /[\-{}\[\]+?.,\\\^$|#\s]/g;
       
  1481 
       
  1482   // Set up all inheritable **Backbone.Router** properties and methods.
       
  1483   _.extend(Router.prototype, Events, {
       
  1484 
       
  1485     // Initialize is an empty function by default. Override it with your own
       
  1486     // initialization logic.
       
  1487     initialize: function(){},
       
  1488 
       
  1489     // Manually bind a single named route to a callback. For example:
       
  1490     //
       
  1491     //     this.route('search/:query/p:num', 'search', function(query, num) {
       
  1492     //       ...
       
  1493     //     });
       
  1494     //
       
  1495     route: function(route, name, callback) {
       
  1496       if (!_.isRegExp(route)) route = this._routeToRegExp(route);
       
  1497       if (_.isFunction(name)) {
       
  1498         callback = name;
       
  1499         name = '';
       
  1500       }
       
  1501       if (!callback) callback = this[name];
       
  1502       var router = this;
       
  1503       Backbone.history.route(route, function(fragment) {
       
  1504         var args = router._extractParameters(route, fragment);
       
  1505         if (router.execute(callback, args, name) !== false) {
       
  1506           router.trigger.apply(router, ['route:' + name].concat(args));
       
  1507           router.trigger('route', name, args);
       
  1508           Backbone.history.trigger('route', router, name, args);
       
  1509         }
       
  1510       });
       
  1511       return this;
       
  1512     },
       
  1513 
       
  1514     // Execute a route handler with the provided parameters.  This is an
       
  1515     // excellent place to do pre-route setup or post-route cleanup.
       
  1516     execute: function(callback, args, name) {
       
  1517       if (callback) callback.apply(this, args);
       
  1518     },
       
  1519 
       
  1520     // Simple proxy to `Backbone.history` to save a fragment into the history.
       
  1521     navigate: function(fragment, options) {
       
  1522       Backbone.history.navigate(fragment, options);
       
  1523       return this;
       
  1524     },
       
  1525 
       
  1526     // Bind all defined routes to `Backbone.history`. We have to reverse the
       
  1527     // order of the routes here to support behavior where the most general
       
  1528     // routes can be defined at the bottom of the route map.
       
  1529     _bindRoutes: function() {
       
  1530       if (!this.routes) return;
       
  1531       this.routes = _.result(this, 'routes');
       
  1532       var route, routes = _.keys(this.routes);
       
  1533       while ((route = routes.pop()) != null) {
       
  1534         this.route(route, this.routes[route]);
       
  1535       }
       
  1536     },
       
  1537 
       
  1538     // Convert a route string into a regular expression, suitable for matching
       
  1539     // against the current location hash.
       
  1540     _routeToRegExp: function(route) {
       
  1541       route = route.replace(escapeRegExp, '\\$&')
       
  1542                    .replace(optionalParam, '(?:$1)?')
       
  1543                    .replace(namedParam, function(match, optional) {
       
  1544                      return optional ? match : '([^/?]+)';
       
  1545                    })
       
  1546                    .replace(splatParam, '([^?]*?)');
       
  1547       return new RegExp('^' + route + '(?:\\?([\\s\\S]*))?$');
       
  1548     },
       
  1549 
       
  1550     // Given a route, and a URL fragment that it matches, return the array of
       
  1551     // extracted decoded parameters. Empty or unmatched parameters will be
       
  1552     // treated as `null` to normalize cross-browser behavior.
       
  1553     _extractParameters: function(route, fragment) {
       
  1554       var params = route.exec(fragment).slice(1);
       
  1555       return _.map(params, function(param, i) {
       
  1556         // Don't decode the search params.
       
  1557         if (i === params.length - 1) return param || null;
       
  1558         return param ? decodeURIComponent(param) : null;
       
  1559       });
       
  1560     }
       
  1561 
       
  1562   });
       
  1563 
       
  1564   // Backbone.History
       
  1565   // ----------------
       
  1566 
       
  1567   // Handles cross-browser history management, based on either
       
  1568   // [pushState](http://diveintohtml5.info/history.html) and real URLs, or
       
  1569   // [onhashchange](https://developer.mozilla.org/en-US/docs/DOM/window.onhashchange)
       
  1570   // and URL fragments. If the browser supports neither (old IE, natch),
       
  1571   // falls back to polling.
       
  1572   var History = Backbone.History = function() {
       
  1573     this.handlers = [];
       
  1574     this.checkUrl = _.bind(this.checkUrl, this);
       
  1575 
       
  1576     // Ensure that `History` can be used outside of the browser.
       
  1577     if (typeof window !== 'undefined') {
       
  1578       this.location = window.location;
       
  1579       this.history = window.history;
       
  1580     }
       
  1581   };
       
  1582 
       
  1583   // Cached regex for stripping a leading hash/slash and trailing space.
       
  1584   var routeStripper = /^[#\/]|\s+$/g;
       
  1585 
       
  1586   // Cached regex for stripping leading and trailing slashes.
       
  1587   var rootStripper = /^\/+|\/+$/g;
       
  1588 
       
  1589   // Cached regex for stripping urls of hash.
       
  1590   var pathStripper = /#.*$/;
       
  1591 
       
  1592   // Has the history handling already been started?
       
  1593   History.started = false;
       
  1594 
       
  1595   // Set up all inheritable **Backbone.History** properties and methods.
       
  1596   _.extend(History.prototype, Events, {
       
  1597 
       
  1598     // The default interval to poll for hash changes, if necessary, is
       
  1599     // twenty times a second.
       
  1600     interval: 50,
       
  1601 
       
  1602     // Are we at the app root?
       
  1603     atRoot: function() {
       
  1604       var path = this.location.pathname.replace(/[^\/]$/, '$&/');
       
  1605       return path === this.root && !this.getSearch();
       
  1606     },
       
  1607 
       
  1608     // Does the pathname match the root?
       
  1609     matchRoot: function() {
       
  1610       var path = this.decodeFragment(this.location.pathname);
       
  1611       var rootPath = path.slice(0, this.root.length - 1) + '/';
       
  1612       return rootPath === this.root;
       
  1613     },
       
  1614 
       
  1615     // Unicode characters in `location.pathname` are percent encoded so they're
       
  1616     // decoded for comparison. `%25` should not be decoded since it may be part
       
  1617     // of an encoded parameter.
       
  1618     decodeFragment: function(fragment) {
       
  1619       return decodeURI(fragment.replace(/%25/g, '%2525'));
       
  1620     },
       
  1621 
       
  1622     // In IE6, the hash fragment and search params are incorrect if the
       
  1623     // fragment contains `?`.
       
  1624     getSearch: function() {
       
  1625       var match = this.location.href.replace(/#.*/, '').match(/\?.+/);
       
  1626       return match ? match[0] : '';
       
  1627     },
       
  1628 
       
  1629     // Gets the true hash value. Cannot use location.hash directly due to bug
       
  1630     // in Firefox where location.hash will always be decoded.
       
  1631     getHash: function(window) {
       
  1632       var match = (window || this).location.href.match(/#(.*)$/);
       
  1633       return match ? match[1] : '';
       
  1634     },
       
  1635 
       
  1636     // Get the pathname and search params, without the root.
       
  1637     getPath: function() {
       
  1638       var path = this.decodeFragment(
       
  1639         this.location.pathname + this.getSearch()
       
  1640       ).slice(this.root.length - 1);
       
  1641       return path.charAt(0) === '/' ? path.slice(1) : path;
       
  1642     },
       
  1643 
       
  1644     // Get the cross-browser normalized URL fragment from the path or hash.
       
  1645     getFragment: function(fragment) {
       
  1646       if (fragment == null) {
       
  1647         if (this._usePushState || !this._wantsHashChange) {
       
  1648           fragment = this.getPath();
       
  1649         } else {
       
  1650           fragment = this.getHash();
       
  1651         }
       
  1652       }
       
  1653       return fragment.replace(routeStripper, '');
       
  1654     },
       
  1655 
       
  1656     // Start the hash change handling, returning `true` if the current URL matches
       
  1657     // an existing route, and `false` otherwise.
       
  1658     start: function(options) {
       
  1659       if (History.started) throw new Error('Backbone.history has already been started');
       
  1660       History.started = true;
       
  1661 
       
  1662       // Figure out the initial configuration. Do we need an iframe?
       
  1663       // Is pushState desired ... is it available?
       
  1664       this.options          = _.extend({root: '/'}, this.options, options);
       
  1665       this.root             = this.options.root;
       
  1666       this._wantsHashChange = this.options.hashChange !== false;
       
  1667       this._hasHashChange   = 'onhashchange' in window && (document.documentMode === void 0 || document.documentMode > 7);
       
  1668       this._useHashChange   = this._wantsHashChange && this._hasHashChange;
       
  1669       this._wantsPushState  = !!this.options.pushState;
       
  1670       this._hasPushState    = !!(this.history && this.history.pushState);
       
  1671       this._usePushState    = this._wantsPushState && this._hasPushState;
       
  1672       this.fragment         = this.getFragment();
       
  1673 
       
  1674       // Normalize root to always include a leading and trailing slash.
       
  1675       this.root = ('/' + this.root + '/').replace(rootStripper, '/');
       
  1676 
       
  1677       // Transition from hashChange to pushState or vice versa if both are
       
  1678       // requested.
       
  1679       if (this._wantsHashChange && this._wantsPushState) {
       
  1680 
       
  1681         // If we've started off with a route from a `pushState`-enabled
       
  1682         // browser, but we're currently in a browser that doesn't support it...
       
  1683         if (!this._hasPushState && !this.atRoot()) {
       
  1684           var rootPath = this.root.slice(0, -1) || '/';
       
  1685           this.location.replace(rootPath + '#' + this.getPath());
       
  1686           // Return immediately as browser will do redirect to new url
       
  1687           return true;
       
  1688 
       
  1689         // Or if we've started out with a hash-based route, but we're currently
       
  1690         // in a browser where it could be `pushState`-based instead...
       
  1691         } else if (this._hasPushState && this.atRoot()) {
       
  1692           this.navigate(this.getHash(), {replace: true});
       
  1693         }
       
  1694 
       
  1695       }
       
  1696 
       
  1697       // Proxy an iframe to handle location events if the browser doesn't
       
  1698       // support the `hashchange` event, HTML5 history, or the user wants
       
  1699       // `hashChange` but not `pushState`.
       
  1700       if (!this._hasHashChange && this._wantsHashChange && !this._usePushState) {
       
  1701         this.iframe = document.createElement('iframe');
       
  1702         this.iframe.src = 'javascript:0';
       
  1703         this.iframe.style.display = 'none';
       
  1704         this.iframe.tabIndex = -1;
       
  1705         var body = document.body;
       
  1706         // Using `appendChild` will throw on IE < 9 if the document is not ready.
       
  1707         var iWindow = body.insertBefore(this.iframe, body.firstChild).contentWindow;
       
  1708         iWindow.document.open();
       
  1709         iWindow.document.close();
       
  1710         iWindow.location.hash = '#' + this.fragment;
       
  1711       }
       
  1712 
       
  1713       // Add a cross-platform `addEventListener` shim for older browsers.
       
  1714       var addEventListener = window.addEventListener || function(eventName, listener) {
       
  1715         return attachEvent('on' + eventName, listener);
       
  1716       };
       
  1717 
       
  1718       // Depending on whether we're using pushState or hashes, and whether
       
  1719       // 'onhashchange' is supported, determine how we check the URL state.
       
  1720       if (this._usePushState) {
       
  1721         addEventListener('popstate', this.checkUrl, false);
       
  1722       } else if (this._useHashChange && !this.iframe) {
       
  1723         addEventListener('hashchange', this.checkUrl, false);
       
  1724       } else if (this._wantsHashChange) {
       
  1725         this._checkUrlInterval = setInterval(this.checkUrl, this.interval);
       
  1726       }
       
  1727 
       
  1728       if (!this.options.silent) return this.loadUrl();
       
  1729     },
       
  1730 
       
  1731     // Disable Backbone.history, perhaps temporarily. Not useful in a real app,
       
  1732     // but possibly useful for unit testing Routers.
       
  1733     stop: function() {
       
  1734       // Add a cross-platform `removeEventListener` shim for older browsers.
       
  1735       var removeEventListener = window.removeEventListener || function(eventName, listener) {
       
  1736         return detachEvent('on' + eventName, listener);
       
  1737       };
       
  1738 
       
  1739       // Remove window listeners.
       
  1740       if (this._usePushState) {
       
  1741         removeEventListener('popstate', this.checkUrl, false);
       
  1742       } else if (this._useHashChange && !this.iframe) {
       
  1743         removeEventListener('hashchange', this.checkUrl, false);
       
  1744       }
       
  1745 
       
  1746       // Clean up the iframe if necessary.
       
  1747       if (this.iframe) {
       
  1748         document.body.removeChild(this.iframe);
       
  1749         this.iframe = null;
       
  1750       }
       
  1751 
       
  1752       // Some environments will throw when clearing an undefined interval.
       
  1753       if (this._checkUrlInterval) clearInterval(this._checkUrlInterval);
       
  1754       History.started = false;
       
  1755     },
       
  1756 
       
  1757     // Add a route to be tested when the fragment changes. Routes added later
       
  1758     // may override previous routes.
       
  1759     route: function(route, callback) {
       
  1760       this.handlers.unshift({route: route, callback: callback});
       
  1761     },
       
  1762 
       
  1763     // Checks the current URL to see if it has changed, and if it has,
       
  1764     // calls `loadUrl`, normalizing across the hidden iframe.
       
  1765     checkUrl: function(e) {
       
  1766       var current = this.getFragment();
       
  1767 
       
  1768       // If the user pressed the back button, the iframe's hash will have
       
  1769       // changed and we should use that for comparison.
       
  1770       if (current === this.fragment && this.iframe) {
       
  1771         current = this.getHash(this.iframe.contentWindow);
       
  1772       }
       
  1773 
       
  1774       if (current === this.fragment) return false;
       
  1775       if (this.iframe) this.navigate(current);
       
  1776       this.loadUrl();
       
  1777     },
       
  1778 
       
  1779     // Attempt to load the current URL fragment. If a route succeeds with a
       
  1780     // match, returns `true`. If no defined routes matches the fragment,
       
  1781     // returns `false`.
       
  1782     loadUrl: function(fragment) {
       
  1783       // If the root doesn't match, no routes can match either.
       
  1784       if (!this.matchRoot()) return false;
       
  1785       fragment = this.fragment = this.getFragment(fragment);
       
  1786       return _.some(this.handlers, function(handler) {
       
  1787         if (handler.route.test(fragment)) {
       
  1788           handler.callback(fragment);
       
  1789           return true;
       
  1790         }
       
  1791       });
       
  1792     },
       
  1793 
       
  1794     // Save a fragment into the hash history, or replace the URL state if the
       
  1795     // 'replace' option is passed. You are responsible for properly URL-encoding
       
  1796     // the fragment in advance.
       
  1797     //
       
  1798     // The options object can contain `trigger: true` if you wish to have the
       
  1799     // route callback be fired (not usually desirable), or `replace: true`, if
       
  1800     // you wish to modify the current URL without adding an entry to the history.
       
  1801     navigate: function(fragment, options) {
       
  1802       if (!History.started) return false;
       
  1803       if (!options || options === true) options = {trigger: !!options};
       
  1804 
       
  1805       // Normalize the fragment.
       
  1806       fragment = this.getFragment(fragment || '');
       
  1807 
       
  1808       // Don't include a trailing slash on the root.
       
  1809       var rootPath = this.root;
       
  1810       if (fragment === '' || fragment.charAt(0) === '?') {
       
  1811         rootPath = rootPath.slice(0, -1) || '/';
       
  1812       }
       
  1813       var url = rootPath + fragment;
       
  1814 
       
  1815       // Strip the hash and decode for matching.
       
  1816       fragment = this.decodeFragment(fragment.replace(pathStripper, ''));
       
  1817 
       
  1818       if (this.fragment === fragment) return;
       
  1819       this.fragment = fragment;
       
  1820 
       
  1821       // If pushState is available, we use it to set the fragment as a real URL.
       
  1822       if (this._usePushState) {
       
  1823         this.history[options.replace ? 'replaceState' : 'pushState']({}, document.title, url);
       
  1824 
       
  1825       // If hash changes haven't been explicitly disabled, update the hash
       
  1826       // fragment to store history.
       
  1827       } else if (this._wantsHashChange) {
       
  1828         this._updateHash(this.location, fragment, options.replace);
       
  1829         if (this.iframe && fragment !== this.getHash(this.iframe.contentWindow)) {
       
  1830           var iWindow = this.iframe.contentWindow;
       
  1831 
       
  1832           // Opening and closing the iframe tricks IE7 and earlier to push a
       
  1833           // history entry on hash-tag change.  When replace is true, we don't
       
  1834           // want this.
       
  1835           if (!options.replace) {
       
  1836             iWindow.document.open();
       
  1837             iWindow.document.close();
       
  1838           }
       
  1839 
       
  1840           this._updateHash(iWindow.location, fragment, options.replace);
       
  1841         }
       
  1842 
       
  1843       // If you've told us that you explicitly don't want fallback hashchange-
       
  1844       // based history, then `navigate` becomes a page refresh.
       
  1845       } else {
       
  1846         return this.location.assign(url);
       
  1847       }
       
  1848       if (options.trigger) return this.loadUrl(fragment);
       
  1849     },
       
  1850 
       
  1851     // Update the hash location, either replacing the current entry, or adding
       
  1852     // a new one to the browser history.
       
  1853     _updateHash: function(location, fragment, replace) {
       
  1854       if (replace) {
       
  1855         var href = location.href.replace(/(javascript:|#).*$/, '');
       
  1856         location.replace(href + '#' + fragment);
       
  1857       } else {
       
  1858         // Some browsers require that `hash` contains a leading #.
       
  1859         location.hash = '#' + fragment;
       
  1860       }
       
  1861     }
       
  1862 
       
  1863   });
       
  1864 
       
  1865   // Create the default Backbone.history.
       
  1866   Backbone.history = new History;
       
  1867 
       
  1868   // Helpers
       
  1869   // -------
       
  1870 
       
  1871   // Helper function to correctly set up the prototype chain for subclasses.
       
  1872   // Similar to `goog.inherits`, but uses a hash of prototype properties and
       
  1873   // class properties to be extended.
       
  1874   var extend = function(protoProps, staticProps) {
       
  1875     var parent = this;
       
  1876     var child;
       
  1877 
       
  1878     // The constructor function for the new subclass is either defined by you
       
  1879     // (the "constructor" property in your `extend` definition), or defaulted
       
  1880     // by us to simply call the parent constructor.
       
  1881     if (protoProps && _.has(protoProps, 'constructor')) {
       
  1882       child = protoProps.constructor;
       
  1883     } else {
       
  1884       child = function(){ return parent.apply(this, arguments); };
       
  1885     }
       
  1886 
       
  1887     // Add static properties to the constructor function, if supplied.
       
  1888     _.extend(child, parent, staticProps);
       
  1889 
       
  1890     // Set the prototype chain to inherit from `parent`, without calling
       
  1891     // `parent`'s constructor function and add the prototype properties.
       
  1892     child.prototype = _.create(parent.prototype, protoProps);
       
  1893     child.prototype.constructor = child;
       
  1894 
       
  1895     // Set a convenience property in case the parent's prototype is needed
       
  1896     // later.
       
  1897     child.__super__ = parent.prototype;
       
  1898 
       
  1899     return child;
       
  1900   };
       
  1901 
       
  1902   // Set up inheritance for the model, collection, router, view and history.
       
  1903   Model.extend = Collection.extend = Router.extend = View.extend = History.extend = extend;
       
  1904 
       
  1905   // Throw an error when a URL is needed, and none is supplied.
       
  1906   var urlError = function() {
       
  1907     throw new Error('A "url" property or function must be specified');
       
  1908   };
       
  1909 
       
  1910   // Wrap an optional error callback with a fallback error event.
       
  1911   var wrapError = function(model, options) {
       
  1912     var error = options.error;
       
  1913     options.error = function(resp) {
       
  1914       if (error) error.call(options.context, model, resp, options);
       
  1915       model.trigger('error', model, resp, options);
       
  1916     };
       
  1917   };
       
  1918 
       
  1919   return Backbone;
       
  1920 });