backbone.js 

Backbone.js 0.9.2

             		           
                               
                            
                                
               
(c) 2010-2012 Jeremy Ashkenas, DocumentCloud Inc.
Backbone may be freely distributed under the MIT license.
For all details and documentation:
http://backbonejs.org

             		                            
(function(){
             		           
                               
                            
                                
               
Initial Setup
             		                            
             		           
                               
                            
                                
               
Save a reference to the global object (window in the browser, global
on the server).
             		                            
  var root = this;
             		           
                               
                            
                                
               
Save the previous value of the Backbone variable, so that it can be
restored later on, if noConflict is used.
             		                            
  var previousBackbone = root.Backbone;
             		           
                               
                            
                                
               
Create a local reference to slice/splice.
             		                            
  var slice = Array.prototype.slice;
  var splice = Array.prototype.splice;
             		           
                               
                            
                                
               
The top-level namespace. All public Backbone classes and modules will
be attached to this. Exported for both CommonJS and the browser.
             		                            
  var Backbone;
  if (typeof exports !== 'undefined') {
    Backbone = exports;
  } else {
    Backbone = root.Backbone = {};
  }
             		           
                               
                            
                                
               
Current version of the library. Keep in sync with package.json.
             		                            
  Backbone.VERSION = '0.9.2';
             		           
                               
                            
                                
               
Require Underscore, if we're on the server, and it's not already present.
             		                            
  var _ = root._;
  if (!_ && (typeof require !== 'undefined')) _ = require('underscore');
             		           
                               
                            
                                
               
For Backbone's purposes, jQuery, Zepto, or Ender owns the $ variable.
             		                            
  var $ = root.jQuery || root.Zepto || root.ender;
             		           
                               
                            
                                
               
Set the JavaScript library that will be used for DOM manipulation and
Ajax calls (a.k.a. the $ variable). By default Backbone will use: jQuery,
Zepto, or Ender; but the setDomLibrary() method lets you inject an
alternate JavaScript library (or a mock library for testing your views
outside of a browser).
             		                            
  Backbone.setDomLibrary = function(lib) {
    $ = lib;
  };
             		           
                               
                            
                                
               
Runs Backbone.js in noConflict mode, returning the Backbone variable
to its previous owner. Returns a reference to this Backbone object.
             		                            
  Backbone.noConflict = function() {
    root.Backbone = previousBackbone;
    return this;
  };
             		           
                               
                            
                                
               
Turn on emulateHTTP to support legacy HTTP servers. Setting this option
will fake "PUT" and "DELETE" requests via the _method parameter and
set a X-Http-Method-Override header.
             		                            
  Backbone.emulateHTTP = false;
             		           
                               
                            
                                
               
Turn on emulateJSON to support legacy servers that can't deal with direct
application/json requests ... will encode the body as
application/x-www-form-urlencoded instead and will send the model in a
form param named model.
             		                            
  Backbone.emulateJSON = false;
             		           
                               
                            
                                
               
Backbone.Events
             		                            
             		           
                               
                            
                                
               
Regular expression used to split event strings
             		                            
  var eventSplitter = /\s+/;
             		           
                               
                            
                                
               
A module that can be mixed in to any object in order to provide it with
custom events. You may bind with on or remove with off callback functions
to an event; trigger`-ing an event fires all callbacks in succession.



var object = {};
_.extend(object, Backbone.Events);
object.on('expand', function(){ alert('expanded'); });
object.trigger('expand');

             		                            
  var Events = Backbone.Events = {
             		           
                               
                            
                                
               
Bind one or more space separated events, events, to a callback
function. Passing "all" will bind the callback to all events fired.
             		                            
    on: function(events, callback, context) {

      var calls, event, node, tail, list;
      if (!callback) return this;
      events = events.split(eventSplitter);
      calls = this._callbacks || (this._callbacks = {});
             		           
                               
                            
                                
               
Create an immutable callback list, allowing traversal during
modification.  The tail is an empty object that will always be used
as the next node.
             		                            
      while (event = events.shift()) {
        list = calls[event];
        node = list ? list.tail : {};
        node.next = tail = {};
        node.context = context;
        node.callback = callback;
        calls[event] = {tail: tail, next: list ? list.next : node};
      }

      return this;
    },
             		           
                               
                            
                                
               
Remove one or many callbacks. If context is null, removes all callbacks
with that function. If callback is null, removes all callbacks for the
event. If events is null, removes all bound callbacks for all events.
             		                            
    off: function(events, callback, context) {
      var event, calls, node, tail, cb, ctx;
             		           
                               
                            
                                
               
No events, or removing all events.
             		                            
      if (!(calls = this._callbacks)) return;
      if (!(events || callback || context)) {
        delete this._callbacks;
        return this;
      }
             		           
                               
                            
                                
               
Loop through the listed events and contexts, splicing them out of the
linked list of callbacks if appropriate.
             		                            
      events = events ? events.split(eventSplitter) : _.keys(calls);
      while (event = events.shift()) {
        node = calls[event];
        delete calls[event];
        if (!node || !(callback || context)) continue;
             		           
                               
                            
                                
               
Create a new list, omitting the indicated callbacks.
             		                            
        tail = node.tail;
        while ((node = node.next) !== tail) {
          cb = node.callback;
          ctx = node.context;
          if ((callback && cb !== callback) || (context && ctx !== context)) {
            this.on(event, cb, ctx);
          }
        }
      }

      return this;
    },
             		           
                               
                            
                                
               
Trigger one or many events, firing all bound callbacks. Callbacks are
passed the same arguments as trigger is, apart from the event name
(unless you're listening on "all", which will cause your callback to
receive the true name of the event as the first argument).
             		                            
    trigger: function(events) {
      var event, node, calls, tail, args, all, rest;
      if (!(calls = this._callbacks)) return this;
      all = calls.all;
      events = events.split(eventSplitter);
      rest = slice.call(arguments, 1);
             		           
                               
                            
                                
               
For each event, walk through the linked list of callbacks twice,
first to trigger the event, then to trigger any "all" callbacks.
             		                            
      while (event = events.shift()) {
        if (node = calls[event]) {
          tail = node.tail;
          while ((node = node.next) !== tail) {
            node.callback.apply(node.context || this, rest);
          }
        }
        if (node = all) {
          tail = node.tail;
          args = [event].concat(rest);
          while ((node = node.next) !== tail) {
            node.callback.apply(node.context || this, args);
          }
        }
      }

      return this;
    }

  };
             		           
                               
                            
                                
               
Aliases for backwards compatibility.
             		                            
  Events.bind   = Events.on;
  Events.unbind = Events.off;
             		           
                               
                            
                                
               
Backbone.Model
             		                            
             		           
                               
                            
                                
               
Create a new model, with defined attributes. A client id (cid)
is automatically generated and assigned for you.
             		                            
  var Model = Backbone.Model = function(attributes, options) {
    var defaults;
    attributes || (attributes = {});
    if (options && options.parse) attributes = this.parse(attributes);
    if (defaults = getValue(this, 'defaults')) {
      attributes = _.extend({}, defaults, attributes);
    }
    if (options && options.collection) this.collection = options.collection;
    this.attributes = {};
    this._escapedAttributes = {};
    this.cid = _.uniqueId('c');
    this.changed = {};
    this._silent = {};
    this._pending = {};
    this.set(attributes, {silent: true});
             		           
                               
                            
                                
               
Reset change tracking.
             		                            
    this.changed = {};
    this._silent = {};
    this._pending = {};
    this._previousAttributes = _.clone(this.attributes);
    this.initialize.apply(this, arguments);
  };
             		           
                               
                            
                                
               
Attach all inheritable methods to the Model prototype.
             		                            
  _.extend(Model.prototype, Events, {
             		           
                               
                            
                                
               
A hash of attributes whose current and previous value differ.
             		                            
    changed: null,
             		           
                               
                            
                                
               
A hash of attributes that have silently changed since the last time
change was called.  Will become pending attributes on the next call.
             		                            
    _silent: null,
             		           
                               
                            
                                
               
A hash of attributes that have changed since the last 'change' event
began.
             		                            
    _pending: null,
             		           
                               
                            
                                
               
The default name for the JSON id attribute is "id". MongoDB and
CouchDB users may want to set this to "_id".
             		                            
    idAttribute: 'id',
             		           
                               
                            
                                
               
Initialize is an empty function by default. Override it with your own
initialization logic.
             		                            
    initialize: function(){},
             		           
                               
                            
                                
               
Return a copy of the model's attributes object.
             		                            
    toJSON: function(options) {
      return _.clone(this.attributes);
    },
             		           
                               
                            
                                
               
Get the value of an attribute.
             		                            
    get: function(attr) {
      return this.attributes[attr];
    },
             		           
                               
                            
                                
               
Get the HTML-escaped value of an attribute.
             		                            
    escape: function(attr) {
      var html;
      if (html = this._escapedAttributes[attr]) return html;
      var val = this.get(attr);
      return this._escapedAttributes[attr] = _.escape(val == null ? '' : '' + val);
    },
             		           
                               
                            
                                
               
Returns true if the attribute contains a value that is not null
or undefined.
             		                            
    has: function(attr) {
      return this.get(attr) != null;
    },
             		           
                               
                            
                                
               
Set a hash of model attributes on the object, firing "change" unless
you choose to silence it.
             		                            
    set: function(key, value, options) {
      var attrs, attr, val;
             		           
                               
                            
                                
               
Handle both
             		                            
      if (_.isObject(key) || key == null) {
        attrs = key;
        options = value;
      } else {
        attrs = {};
        attrs[key] = value;
      }
             		           
                               
                            
                                
               
Extract attributes and options.
             		                            
      options || (options = {});
      if (!attrs) return this;
      if (attrs instanceof Model) attrs = attrs.attributes;
      if (options.unset) for (attr in attrs) attrs[attr] = void 0;
             		           
                               
                            
                                
               
Run validation.
             		                            
      if (!this._validate(attrs, options)) return false;
             		           
                               
                            
                                
               
Check for changes of id.
             		                            
      if (this.idAttribute in attrs) this.id = attrs[this.idAttribute];

      var changes = options.changes = {};
      var now = this.attributes;
      var escaped = this._escapedAttributes;
      var prev = this._previousAttributes || {};
             		           
                               
                            
                                
               
For each set attribute...
             		                            
      for (attr in attrs) {
        val = attrs[attr];
             		           
                               
                            
                                
               
If the new and current value differ, record the change.
             		                            
        if (!_.isEqual(now[attr], val) || (options.unset && _.has(now, attr))) {
          delete escaped[attr];
          (options.silent ? this._silent : changes)[attr] = true;
        }
             		           
                               
                            
                                
               
Update or delete the current value.
             		                            
        options.unset ? delete now[attr] : now[attr] = val;
             		           
                               
                            
                                
               
If the new and previous value differ, record the change.  If not,
then remove changes for this attribute.
             		                            
        if (!_.isEqual(prev[attr], val) || (_.has(now, attr) != _.has(prev, attr))) {
          this.changed[attr] = val;
          if (!options.silent) this._pending[attr] = true;
        } else {
          delete this.changed[attr];
          delete this._pending[attr];
        }
      }
             		           
                               
                            
                                
               
Fire the "change" events.
             		                            
      if (!options.silent) this.change(options);
      return this;
    },
             		           
                               
                            
                                
               
Remove an attribute from the model, firing "change" unless you choose
to silence it. unset is a noop if the attribute doesn't exist.
             		                            
    unset: function(attr, options) {
      (options || (options = {})).unset = true;
      return this.set(attr, null, options);
    },
             		           
                               
                            
                                
               
Clear all attributes on the model, firing "change" unless you choose
to silence it.
             		                            
    clear: function(options) {
      (options || (options = {})).unset = true;
      return this.set(_.clone(this.attributes), options);
    },
             		           
                               
                            
                                
               
Fetch the model from the server. If the server's representation of the
model differs from its current attributes, they will be overriden,
triggering a "change" event.
             		                            
    fetch: function(options) {
      options = options ? _.clone(options) : {};
      var model = this;
      var success = options.success;
      options.success = function(resp, status, xhr) {
        if (!model.set(model.parse(resp, xhr), options)) return false;
        if (success) success(model, resp);
      };
      options.error = Backbone.wrapError(options.error, model, options);
      return (this.sync || Backbone.sync).call(this, 'read', this, options);
    },
             		           
                               
                            
                                
               
Set a hash of model attributes, and sync the model to the server.
If the server returns an attributes hash that differs, the model's
state will be set again.
             		                            
    save: function(key, value, options) {
      var attrs, current;
             		           
                               
                            
                                
               
Handle both ("key", value) and ({key: value}) -style calls.
             		                            
      if (_.isObject(key) || key == null) {
        attrs = key;
        options = value;
      } else {
        attrs = {};
        attrs[key] = value;
      }
      options = options ? _.clone(options) : {};
             		           
                               
                            
                                
               
If we're "wait"-ing to set changed attributes, validate early.
             		                            
      if (options.wait) {
        if (!this._validate(attrs, options)) return false;
        current = _.clone(this.attributes);
      }
             		           
                               
                            
                                
               
Regular saves set attributes before persisting to the server.
             		                            
      var silentOptions = _.extend({}, options, {silent: true});
      if (attrs && !this.set(attrs, options.wait ? silentOptions : options)) {
        return false;
      }
             		           
                               
                            
                                
               
After a successful server-side save, the client is (optionally)
updated with the server-side state.
             		                            
      var model = this;
      var success = options.success;
      options.success = function(resp, status, xhr) {
        var serverAttrs = model.parse(resp, xhr);
        if (options.wait) {
          delete options.wait;
          serverAttrs = _.extend(attrs || {}, serverAttrs);
        }
        if (!model.set(serverAttrs, options)) return false;
        if (success) {
          success(model, resp);
        } else {
          model.trigger('sync', model, resp, options);
        }
      };
             		           
                               
                            
                                
               
Finish configuring and sending the Ajax request.
             		                            
      options.error = Backbone.wrapError(options.error, model, options);
      var method = this.isNew() ? 'create' : 'update';
      var xhr = (this.sync || Backbone.sync).call(this, method, this, options);
      if (options.wait) this.set(current, silentOptions);
      return xhr;
    },
             		           
                               
                            
                                
               
Destroy this model on the server if it was already persisted.
Optimistically removes the model from its collection, if it has one.
If wait: true is passed, waits for the server to respond before removal.
             		                            
    destroy: function(options) {
      options = options ? _.clone(options) : {};
      var model = this;
      var success = options.success;

      var triggerDestroy = function() {
        model.trigger('destroy', model, model.collection, options);
      };

      if (this.isNew()) {
        triggerDestroy();
        return false;
      }

      options.success = function(resp) {
        if (options.wait) triggerDestroy();
        if (success) {
          success(model, resp);
        } else {
          model.trigger('sync', model, resp, options);
        }
      };

      options.error = Backbone.wrapError(options.error, model, options);
      var xhr = (this.sync || Backbone.sync).call(this, 'delete', this, options);
      if (!options.wait) triggerDestroy();
      return xhr;
    },
             		           
                               
                            
                                
               
Default URL for the model's representation on the server -- if you're
using Backbone's restful methods, override this to change the endpoint
that will be called.
             		                            
    url: function() {
      var base = getValue(this, 'urlRoot') || getValue(this.collection, 'url') || urlError();
      if (this.isNew()) return base;
      return base + (base.charAt(base.length - 1) == '/' ? '' : '/') + encodeURIComponent(this.id);
    },
             		           
                               
                            
                                
               
parse converts a response into the hash of attributes to be set on
the model. The default implementation is just to pass the response along.
             		                            
    parse: function(resp, xhr) {
      return resp;
    },
             		           
                               
                            
                                
               
Create a new model with identical attributes to this one.
             		                            
    clone: function() {
      return new this.constructor(this.attributes);
    },
             		           
                               
                            
                                
               
A model is new if it has never been saved to the server, and lacks an id.
             		                            
    isNew: function() {
      return this.id == null;
    },
             		           
                               
                            
                                
               
Call this method to manually fire a "change" event for this model and
a "change:attribute" event for each changed attribute.
Calling this will cause all objects observing the model to update.
             		                            
    change: function(options) {
      options || (options = {});
      var changing = this._changing;
      this._changing = true;
             		           
                               
                            
                                
               
Silent changes become pending changes.
             		                            
      for (var attr in this._silent) this._pending[attr] = true;
             		           
                               
                            
                                
               
Silent changes are triggered.
             		                            
      var changes = _.extend({}, options.changes, this._silent);
      this._silent = {};
      for (var attr in changes) {
        this.trigger('change:' + attr, this, this.get(attr), options);
      }
      if (changing) return this;
             		           
                               
                            
                                
               
Continue firing "change" events while there are pending changes.
             		                            
      while (!_.isEmpty(this._pending)) {
        this._pending = {};
        this.trigger('change', this, options);
             		           
                               
                            
                                
               
Pending and silent changes still remain.
             		                            
        for (var attr in this.changed) {
          if (this._pending[attr] || this._silent[attr]) continue;
          delete this.changed[attr];
        }
        this._previousAttributes = _.clone(this.attributes);
      }

      this._changing = false;
      return this;
    },
             		           
                               
                            
                                
               
Determine if the model has changed since the last "change" event.
If you specify an attribute name, determine if that attribute has changed.
             		                            
    hasChanged: function(attr) {
      if (!arguments.length) return !_.isEmpty(this.changed);
      return _.has(this.changed, attr);
    },
             		           
                               
                            
                                
               
Return an object containing all the attributes that have changed, or
false if there are no changed attributes. Useful for determining what
parts of a view need to be updated and/or what attributes need to be
persisted to the server. Unset attributes will be set to undefined.
You can also pass an attributes object to diff against the model,
determining if there would be a change.
             		                            
    changedAttributes: function(diff) {
      if (!diff) return this.hasChanged() ? _.clone(this.changed) : false;
      var val, changed = false, old = this._previousAttributes;
      for (var attr in diff) {
        if (_.isEqual(old[attr], (val = diff[attr]))) continue;
        (changed || (changed = {}))[attr] = val;
      }
      return changed;
    },
             		           
                               
                            
                                
               
Get the previous value of an attribute, recorded at the time the last
"change" event was fired.
             		                            
    previous: function(attr) {
      if (!arguments.length || !this._previousAttributes) return null;
      return this._previousAttributes[attr];
    },
             		           
                               
                            
                                
               
Get all of the attributes of the model at the time of the previous
"change" event.
             		                            
    previousAttributes: function() {
      return _.clone(this._previousAttributes);
    },
             		           
                               
                            
                                
               
Check if the model is currently in a valid state. It's only possible to
get into an invalid state if you're using silent changes.
             		                            
    isValid: function() {
      return !this.validate(this.attributes);
    },
             		           
                               
                            
                                
               
Run validation against the next complete set of model attributes,
returning true if all is well. If a specific error callback has
been passed, call that instead of firing the general "error" event.
             		                            
    _validate: function(attrs, options) {
      if (options.silent || !this.validate) return true;
      attrs = _.extend({}, this.attributes, attrs);
      var error = this.validate(attrs, options);
      if (!error) return true;
      if (options && options.error) {
        options.error(this, error, options);
      } else {
        this.trigger('error', this, error, options);
      }
      return false;
    }

  });
             		           
                               
                            
                                
               
Backbone.Collection
             		                            
             		           
                               
                            
                                
               
Provides a standard collection class for our sets of models, ordered
or unordered. If a comparator is specified, the Collection will maintain
its models in sort order, as they're added and removed.
             		                            
  var Collection = Backbone.Collection = function(models, options) {
    options || (options = {});
    if (options.model) this.model = options.model;
    if (options.comparator) this.comparator = options.comparator;
    this._reset();
    this.initialize.apply(this, arguments);
    if (models) this.reset(models, {silent: true, parse: options.parse});
  };
             		           
                               
                            
                                
               
Define the Collection's inheritable methods.
             		                            
  _.extend(Collection.prototype, Events, {
             		           
                               
                            
                                
               
The default model for a collection is just a Backbone.Model.
This should be overridden in most cases.
             		                            
    model: Model,
             		           
                               
                            
                                
               
Initialize is an empty function by default. Override it with your own
initialization logic.
             		                            
    initialize: function(){},
             		           
                               
                            
                                
               
The JSON representation of a Collection is an array of the
models' attributes.
             		                            
    toJSON: function(options) {
      return this.map(function(model){ return model.toJSON(options); });
    },
             		           
                               
                            
                                
               
Add a model, or list of models to the set. Pass silent to avoid
firing the add event for every new model.
             		                            
    add: function(models, options) {
      var i, index, length, model, cid, id, cids = {}, ids = {}, dups = [];
      options || (options = {});
      models = _.isArray(models) ? models.slice() : [models];
             		           
                               
                            
                                
               
Begin by turning bare objects into model references, and preventing
invalid models or duplicate models from being added.
             		                            
      for (i = 0, length = models.length; i < length; i++) {
        if (!(model = models[i] = this._prepareModel(models[i], options))) {
          throw new Error("Can't add an invalid model to a collection");
        }
        cid = model.cid;
        id = model.id;
        if (cids[cid] || this._byCid[cid] || ((id != null) && (ids[id] || this._byId[id]))) {
          dups.push(i);
          continue;
        }
        cids[cid] = ids[id] = model;
      }
             		           
                               
                            
                                
               
Remove duplicates.
             		                            
      i = dups.length;
      while (i--) {
        models.splice(dups[i], 1);
      }
             		           
                               
                            
                                
               
Listen to added models' events, and index models for lookup by
id and by cid.
             		                            
      for (i = 0, length = models.length; i < length; i++) {
        (model = models[i]).on('all', this._onModelEvent, this);
        this._byCid[model.cid] = model;
        if (model.id != null) this._byId[model.id] = model;
      }
             		           
                               
                            
                                
               
Insert models into the collection, re-sorting if needed, and triggering
add events unless silenced.
             		                            
      this.length += length;
      index = options.at != null ? options.at : this.models.length;
      splice.apply(this.models, [index, 0].concat(models));
      if (this.comparator) this.sort({silent: true});
      if (options.silent) return this;
      for (i = 0, length = this.models.length; i < length; i++) {
        if (!cids[(model = this.models[i]).cid]) continue;
        options.index = i;
        model.trigger('add', model, this, options);
      }
      return this;
    },
             		           
                               
                            
                                
               
Remove a model, or a list of models from the set. Pass silent to avoid
firing the remove event for every model removed.
             		                            
    remove: function(models, options) {
      var i, l, index, model;
      options || (options = {});
      models = _.isArray(models) ? models.slice() : [models];
      for (i = 0, l = models.length; i < l; i++) {
        model = this.getByCid(models[i]) || this.get(models[i]);
        if (!model) continue;
        delete this._byId[model.id];
        delete this._byCid[model.cid];
        index = this.indexOf(model);
        this.models.splice(index, 1);
        this.length--;
        if (!options.silent) {
          options.index = index;
          model.trigger('remove', model, this, options);
        }
        this._removeReference(model);
      }
      return this;
    },
             		           
                               
                            
                                
               
Add a model to the end of the collection.
             		                            
    push: function(model, options) {
      model = this._prepareModel(model, options);
      this.add(model, options);
      return model;
    },
             		           
                               
                            
                                
               
Remove a model from the end of the collection.
             		                            
    pop: function(options) {
      var model = this.at(this.length - 1);
      this.remove(model, options);
      return model;
    },
             		           
                               
                            
                                
               
Add a model to the beginning of the collection.
             		                            
    unshift: function(model, options) {
      model = this._prepareModel(model, options);
      this.add(model, _.extend({at: 0}, options));
      return model;
    },
             		           
                               
                            
                                
               
Remove a model from the beginning of the collection.
             		                            
    shift: function(options) {
      var model = this.at(0);
      this.remove(model, options);
      return model;
    },
             		           
                               
                            
                                
               
Get a model from the set by id.
             		                            
    get: function(id) {
      if (id == null) return void 0;
      return this._byId[id.id != null ? id.id : id];
    },
             		           
                               
                            
                                
               
Get a model from the set by client id.
             		                            
    getByCid: function(cid) {
      return cid && this._byCid[cid.cid || cid];
    },
             		           
                               
                            
                                
               
Get the model at the given index.
             		                            
    at: function(index) {
      return this.models[index];
    },
             		           
                               
                            
                                
               
Return models with matching attributes. Useful for simple cases of filter.
             		                            
    where: function(attrs) {
      if (_.isEmpty(attrs)) return [];
      return this.filter(function(model) {
        for (var key in attrs) {
          if (attrs[key] !== model.get(key)) return false;
        }
        return true;
      });
    },
             		           
                               
                            
                                
               
Force the collection to re-sort itself. You don't need to call this under
normal circumstances, as the set will maintain sort order as each item
is added.
             		                            
    sort: function(options) {
      options || (options = {});
      if (!this.comparator) throw new Error('Cannot sort a set without a comparator');
      var boundComparator = _.bind(this.comparator, this);
      if (this.comparator.length == 1) {
        this.models = this.sortBy(boundComparator);
      } else {
        this.models.sort(boundComparator);
      }
      if (!options.silent) this.trigger('reset', this, options);
      return this;
    },
             		           
                               
                            
                                
               
Pluck an attribute from each model in the collection.
             		                            
    pluck: function(attr) {
      return _.map(this.models, function(model){ return model.get(attr); });
    },
             		           
                               
                            
                                
               
When you have more items than you want to add or remove individually,
you can reset the entire set with a new list of models, without firing
any add or remove events. Fires reset when finished.
             		                            
    reset: function(models, options) {
      models  || (models = []);
      options || (options = {});
      for (var i = 0, l = this.models.length; i < l; i++) {
        this._removeReference(this.models[i]);
      }
      this._reset();
      this.add(models, _.extend({silent: true}, options));
      if (!options.silent) this.trigger('reset', this, options);
      return this;
    },
             		           
                               
                            
                                
               
Fetch the default set of models for this collection, resetting the
collection when they arrive. If add: true is passed, appends the
models to the collection instead of resetting.
             		                            
    fetch: function(options) {
      options = options ? _.clone(options) : {};
      if (options.parse === undefined) options.parse = true;
      var collection = this;
      var success = options.success;
      options.success = function(resp, status, xhr) {
        collection[options.add ? 'add' : 'reset'](collection.parse(resp, xhr), options);
        if (success) success(collection, resp);
      };
      options.error = Backbone.wrapError(options.error, collection, options);
      return (this.sync || Backbone.sync).call(this, 'read', this, options);
    },
             		           
                               
                            
                                
               
Create a new instance of a model in this collection. Add the model to the
collection immediately, unless wait: true is passed, in which case we
wait for the server to agree.
             		                            
    create: function(model, options) {
      var coll = this;
      options = options ? _.clone(options) : {};
      model = this._prepareModel(model, options);
      if (!model) return false;
      if (!options.wait) coll.add(model, options);
      var success = options.success;
      options.success = function(nextModel, resp, xhr) {
        if (options.wait) coll.add(nextModel, options);
        if (success) {
          success(nextModel, resp);
        } else {
          nextModel.trigger('sync', model, resp, options);
        }
      };
      model.save(null, options);
      return model;
    },
             		           
                               
                            
                                
               
parse converts a response into a list of models to be added to the
collection. The default implementation is just to pass it through.
             		                            
    parse: function(resp, xhr) {
      return resp;
    },
             		           
                               
                            
                                
               
Proxy to _'s chain. Can't be proxied the same way the rest of the
underscore methods are proxied because it relies on the underscore
constructor.
             		                            
    chain: function () {
      return _(this.models).chain();
    },
             		           
                               
                            
                                
               
Reset all internal state. Called when the collection is reset.
             		                            
    _reset: function(options) {
      this.length = 0;
      this.models = [];
      this._byId  = {};
      this._byCid = {};
    },
             		           
                               
                            
                                
               
Prepare a model or hash of attributes to be added to this collection.
             		                            
    _prepareModel: function(model, options) {
      options || (options = {});
      if (!(model instanceof Model)) {
        var attrs = model;
        options.collection = this;
        model = new this.model(attrs, options);
        if (!model._validate(model.attributes, options)) model = false;
      } else if (!model.collection) {
        model.collection = this;
      }
      return model;
    },
             		           
                               
                            
                                
               
Internal method to remove a model's ties to a collection.
             		                            
    _removeReference: function(model) {
      if (this == model.collection) {
        delete model.collection;
      }
      model.off('all', this._onModelEvent, this);
    },
             		           
                               
                            
                                
               
Internal method called every time a model in the set fires an event.
Sets need to update their indexes when models change ids. All other
events simply proxy through. "add" and "remove" events that originate
in other collections are ignored.
             		                            
    _onModelEvent: function(event, model, collection, options) {
      if ((event == 'add' || event == 'remove') && collection != this) return;
      if (event == 'destroy') {
        this.remove(model, options);
      }
      if (model && event === 'change:' + model.idAttribute) {
        delete this._byId[model.previous(model.idAttribute)];
        this._byId[model.id] = model;
      }
      this.trigger.apply(this, arguments);
    }

  });
             		           
                               
                            
                                
               
Underscore methods that we want to implement on the Collection.
             		                            
  var methods = ['forEach', 'each', 'map', 'reduce', 'reduceRight', 'find',
    'detect', 'filter', 'select', 'reject', 'every', 'all', 'some', 'any',
    'include', 'contains', 'invoke', 'max', 'min', 'sortBy', 'sortedIndex',
    'toArray', 'size', 'first', 'initial', 'rest', 'last', 'without', 'indexOf',
    'shuffle', 'lastIndexOf', 'isEmpty', 'groupBy'];
             		           
                               
                            
                                
               
Mix in each Underscore method as a proxy to Collection#models.
             		                            
  _.each(methods, function(method) {
    Collection.prototype[method] = function() {
      return _[method].apply(_, [this.models].concat(_.toArray(arguments)));
    };
  });
             		           
                               
                            
                                
               
Backbone.Router
             		                            
             		           
                               
                            
                                
               
Routers map faux-URLs to actions, and fire events when routes are
matched. Creating a new one sets its routes hash, if not set statically.
             		                            
  var Router = Backbone.Router = function(options) {
    options || (options = {});
    if (options.routes) this.routes = options.routes;
    this._bindRoutes();
    this.initialize.apply(this, arguments);
  };
             		           
                               
                            
                                
               
Cached regular expressions for matching named param parts and splatted
parts of route strings.
             		                            
  var namedParam    = /:\w+/g;
  var splatParam    = /\*\w+/g;
  var escapeRegExp  = /[-[\]{}()+?.,\\^$|#\s]/g;
             		           
                               
                            
                                
               
Set up all inheritable Backbone.Router properties and methods.
             		                            
  _.extend(Router.prototype, Events, {
             		           
                               
                            
                                
               
Initialize is an empty function by default. Override it with your own
initialization logic.
             		                            
    initialize: function(){},
             		           
                               
                            
                                
               
Manually bind a single named route to a callback. For example:



this.route('search/:query/p:num', 'search', function(query, num) {
  ...
});

             		                            
    route: function(route, name, callback) {
      Backbone.history || (Backbone.history = new History);
      if (!_.isRegExp(route)) route = this._routeToRegExp(route);
      if (!callback) callback = this[name];
      Backbone.history.route(route, _.bind(function(fragment) {
        var args = this._extractParameters(route, fragment);
        callback && callback.apply(this, args);
        this.trigger.apply(this, ['route:' + name].concat(args));
        Backbone.history.trigger('route', this, name, args);
      }, this));
      return this;
    },
             		           
                               
                            
                                
               
Simple proxy to Backbone.history to save a fragment into the history.
             		                            
    navigate: function(fragment, options) {
      Backbone.history.navigate(fragment, options);
    },
             		           
                               
                            
                                
               
Bind all defined routes to Backbone.history. We have to reverse the
order of the routes here to support behavior where the most general
routes can be defined at the bottom of the route map.
             		                            
    _bindRoutes: function() {
      if (!this.routes) return;
      var routes = [];
      for (var route in this.routes) {
        routes.unshift([route, this.routes[route]]);
      }
      for (var i = 0, l = routes.length; i < l; i++) {
        this.route(routes[i][0], routes[i][1], this[routes[i][1]]);
      }
    },
             		           
                               
                            
                                
               
Convert a route string into a regular expression, suitable for matching
against the current location hash.
             		                            
    _routeToRegExp: function(route) {
      route = route.replace(escapeRegExp, '\\$&')
                   .replace(namedParam, '([^\/]+)')
                   .replace(splatParam, '(.*?)');
      return new RegExp('^' + route + '$');
    },
             		           
                               
                            
                                
               
Given a route, and a URL fragment that it matches, return the array of
extracted parameters.
             		                            
    _extractParameters: function(route, fragment) {
      return route.exec(fragment).slice(1);
    }

  });
             		           
                               
                            
                                
               
Backbone.History
             		                            
             		           
                               
                            
                                
               
Handles cross-browser history management, based on URL fragments. If the
browser does not support onhashchange, falls back to polling.
             		                            
  var History = Backbone.History = function() {
    this.handlers = [];
    _.bindAll(this, 'checkUrl');
  };
             		           
                               
                            
                                
               
Cached regex for cleaning leading hashes and slashes .
             		                            
  var routeStripper = /^[#\/]/;
             		           
                               
                            
                                
               
Cached regex for detecting MSIE.
             		                            
  var isExplorer = /msie [\w.]+/;
             		           
                               
                            
                                
               
Has the history handling already been started?
             		                            
  History.started = false;
             		           
                               
                            
                                
               
Set up all inheritable Backbone.History properties and methods.
             		                            
  _.extend(History.prototype, Events, {
             		           
                               
                            
                                
               
The default interval to poll for hash changes, if necessary, is
twenty times a second.
             		                            
    interval: 50,
             		           
                               
                            
                                
               
Gets the true hash value. Cannot use location.hash directly due to bug
in Firefox where location.hash will always be decoded.
             		                            
    getHash: function(windowOverride) {
      var loc = windowOverride ? windowOverride.location : window.location;
      var match = loc.href.match(/#(.*)$/);
      return match ? match[1] : '';
    },
             		           
                               
                            
                                
               
Get the cross-browser normalized URL fragment, either from the URL,
the hash, or the override.
             		                            
    getFragment: function(fragment, forcePushState) {
      if (fragment == null) {
        if (this._hasPushState || forcePushState) {
          fragment = window.location.pathname;
          var search = window.location.search;
          if (search) fragment += search;
        } else {
          fragment = this.getHash();
        }
      }
      if (!fragment.indexOf(this.options.root)) fragment = fragment.substr(this.options.root.length);
      return fragment.replace(routeStripper, '');
    },
             		           
                               
                            
                                
               
Start the hash change handling, returning true if the current URL matches
an existing route, and false otherwise.
             		                            
    start: function(options) {
      if (History.started) throw new Error("Backbone.history has already been started");
      History.started = true;
             		           
                               
                            
                                
               
Figure out the initial configuration. Do we need an iframe?
Is pushState desired ... is it available?
             		                            
      this.options          = _.extend({}, {root: '/'}, this.options, options);
      this._wantsHashChange = this.options.hashChange !== false;
      this._wantsPushState  = !!this.options.pushState;
      this._hasPushState    = !!(this.options.pushState && window.history && window.history.pushState);
      var fragment          = this.getFragment();
      var docMode           = document.documentMode;
      var oldIE             = (isExplorer.exec(navigator.userAgent.toLowerCase()) && (!docMode || docMode <= 7));

      if (oldIE) {
        this.iframe = $('<iframe src="javascript:0" tabindex="-1" />').hide().appendTo('body')[0].contentWindow;
        this.navigate(fragment);
      }
             		           
                               
                            
                                
               
Depending on whether we're using pushState or hashes, and whether
'onhashchange' is supported, determine how we check the URL state.
             		                            
      if (this._hasPushState) {
        $(window).bind('popstate', this.checkUrl);
      } else if (this._wantsHashChange && ('onhashchange' in window) && !oldIE) {
        $(window).bind('hashchange', this.checkUrl);
      } else if (this._wantsHashChange) {
        this._checkUrlInterval = setInterval(this.checkUrl, this.interval);
      }
             		           
                               
                            
                                
               
Determine if we need to change the base url, for a pushState link
opened by a non-pushState browser.
             		                            
      this.fragment = fragment;
      var loc = window.location;
      var atRoot  = loc.pathname == this.options.root;
             		           
                               
                            
                                
               
If we've started off with a route from a pushState-enabled browser,
but we're currently in a browser that doesn't support it...
             		                            
      if (this._wantsHashChange && this._wantsPushState && !this._hasPushState && !atRoot) {
        this.fragment = this.getFragment(null, true);
        window.location.replace(this.options.root + '#' + this.fragment);
             		           
                               
                            
                                
               
Return immediately as browser will do redirect to new url
             		                            
        return true;
             		           
                               
                            
                                
               
Or if we've started out with a hash-based route, but we're currently
in a browser where it could be pushState-based instead...
             		                            
      } else if (this._wantsPushState && this._hasPushState && atRoot && loc.hash) {
        this.fragment = this.getHash().replace(routeStripper, '');
        window.history.replaceState({}, document.title, loc.protocol + '//' + loc.host + this.options.root + this.fragment);
      }

      if (!this.options.silent) {
        return this.loadUrl();
      }
    },
             		           
                               
                            
                                
               
Disable Backbone.history, perhaps temporarily. Not useful in a real app,
but possibly useful for unit testing Routers.
             		                            
    stop: function() {
      $(window).unbind('popstate', this.checkUrl).unbind('hashchange', this.checkUrl);
      clearInterval(this._checkUrlInterval);
      History.started = false;
    },
             		           
                               
                            
                                
               
Add a route to be tested when the fragment changes. Routes added later
may override previous routes.
             		                            
    route: function(route, callback) {
      this.handlers.unshift({route: route, callback: callback});
    },
             		           
                               
                            
                                
               
Checks the current URL to see if it has changed, and if it has,
calls loadUrl, normalizing across the hidden iframe.
             		                            
    checkUrl: function(e) {
      var current = this.getFragment();
      if (current == this.fragment && this.iframe) current = this.getFragment(this.getHash(this.iframe));
      if (current == this.fragment) return false;
      if (this.iframe) this.navigate(current);
      this.loadUrl() || this.loadUrl(this.getHash());
    },
             		           
                               
                            
                                
               
Attempt to load the current URL fragment. If a route succeeds with a
match, returns true. If no defined routes matches the fragment,
returns false.
             		                            
    loadUrl: function(fragmentOverride) {
      var fragment = this.fragment = this.getFragment(fragmentOverride);
      var matched = _.any(this.handlers, function(handler) {
        if (handler.route.test(fragment)) {
          handler.callback(fragment);
          return true;
        }
      });
      return matched;
    },
             		           
                               
                            
                                
               
Save a fragment into the hash history, or replace the URL state if the
'replace' option is passed. You are responsible for properly URL-encoding
the fragment in advance.



The options object can contain trigger: true if you wish to have the
route callback be fired (not usually desirable), or replace: true, if
you wish to modify the current URL without adding an entry to the history.
             		                            
    navigate: function(fragment, options) {
      if (!History.started) return false;
      if (!options || options === true) options = {trigger: options};
      var frag = (fragment || '').replace(routeStripper, '');
      if (this.fragment == frag) return;
             		           
                               
                            
                                
               
If pushState is available, we use it to set the fragment as a real URL.
             		                            
      if (this._hasPushState) {
        if (frag.indexOf(this.options.root) != 0) frag = this.options.root + frag;
        this.fragment = frag;
        window.history[options.replace ? 'replaceState' : 'pushState']({}, document.title, frag);
             		           
                               
                            
                                
               
If hash changes haven't been explicitly disabled, update the hash
fragment to store history.
             		                            
      } else if (this._wantsHashChange) {
        this.fragment = frag;
        this._updateHash(window.location, frag, options.replace);
        if (this.iframe && (frag != this.getFragment(this.getHash(this.iframe)))) {
             		           
                               
                            
                                
               
Opening and closing the iframe tricks IE7 and earlier to push a history entry on hash-tag change.
When replace is true, we don't want this.
             		                            
          if(!options.replace) this.iframe.document.open().close();
          this._updateHash(this.iframe.location, frag, options.replace);
        }
             		           
                               
                            
                                
               
If you've told us that you explicitly don't want fallback hashchange-
based history, then navigate becomes a page refresh.
             		                            
      } else {
        window.location.assign(this.options.root + fragment);
      }
      if (options.trigger) this.loadUrl(fragment);
    },
             		           
                               
                            
                                
               
Update the hash location, either replacing the current entry, or adding
a new one to the browser history.
             		                            
    _updateHash: function(location, fragment, replace) {
      if (replace) {
        location.replace(location.toString().replace(/(javascript:|#).*$/, '') + '#' + fragment);
      } else {
        location.hash = fragment;
      }
    }
  });
             		           
                               
                            
                                
               
Backbone.View
             		                            
             		           
                               
                            
                                
               
Creating a Backbone.View creates its initial element outside of the DOM,
if an existing element is not provided...
             		                            
  var View = Backbone.View = function(options) {
    this.cid = _.uniqueId('view');
    this._configure(options || {});
    this._ensureElement();
    this.initialize.apply(this, arguments);
    this.delegateEvents();
  };
             		           
                               
                            
                                
               
Cached regex to split keys for delegate.
             		                            
  var delegateEventSplitter = /^(\S+)\s*(.*)$/;
             		           
                               
                            
                                
               
List of view options to be merged as properties.
             		                            
  var viewOptions = ['model', 'collection', 'el', 'id', 'attributes', 'className', 'tagName'];
             		           
                               
                            
                                
               
Set up all inheritable Backbone.View properties and methods.
             		                            
  _.extend(View.prototype, Events, {
             		           
                               
                            
                                
               
The default tagName of a View's element is "div".
             		                            
    tagName: 'div',
             		           
                               
                            
                                
               
jQuery delegate for element lookup, scoped to DOM elements within the
current view. This should be prefered to global lookups where possible.
             		                            
    $: function(selector) {
      return this.$el.find(selector);
    },
             		           
                               
                            
                                
               
Initialize is an empty function by default. Override it with your own
initialization logic.
             		                            
    initialize: function(){},
             		           
                               
                            
                                
               
render is the core function that your view should override, in order
to populate its element (this.el), with the appropriate HTML. The
convention is for render to always return this.
             		                            
    render: function() {
      return this;
    },
             		           
                               
                            
                                
               
Remove this view from the DOM. Note that the view isn't present in the
DOM by default, so calling this method may be a no-op.
             		                            
    remove: function() {
      this.$el.remove();
      return this;
    },
             		           
                               
                            
                                
               
For small amounts of DOM Elements, where a full-blown template isn't
needed, use make to manufacture elements, one at a time.



var el = this.make('li', {'class': 'row'}, this.model.escape('title'));

             		                            
    make: function(tagName, attributes, content) {
      var el = document.createElement(tagName);
      if (attributes) $(el).attr(attributes);
      if (content) $(el).html(content);
      return el;
    },
             		           
                               
                            
                                
               
Change the view's element (this.el property), including event
re-delegation.
             		                            
    setElement: function(element, delegate) {
      if (this.$el) this.undelegateEvents();
      this.$el = (element instanceof $) ? element : $(element);
      this.el = this.$el[0];
      if (delegate !== false) this.delegateEvents();
      return this;
    },
             		           
                               
                            
                                
               
Set callbacks, where this.events is a hash of



{"event selector": "callback"}



{
  'mousedown .title':  'edit',
  'click .button':     'save'
  'click .open':       function(e) { ... }
}




pairs. Callbacks will be bound to the view, with this set properly.
Uses event delegation for efficiency.
Omitting the selector binds the event to this.el.
This only works for delegate-able events: not focus, blur, and
not change, submit, and reset in Internet Explorer.
             		                            
    delegateEvents: function(events) {
      if (!(events || (events = getValue(this, 'events')))) return;
      this.undelegateEvents();
      for (var key in events) {
        var method = events[key];
        if (!_.isFunction(method)) method = this[events[key]];
        if (!method) throw new Error('Method "' + events[key] + '" does not exist');
        var match = key.match(delegateEventSplitter);
        var eventName = match[1], selector = match[2];
        method = _.bind(method, this);
        eventName += '.delegateEvents' + this.cid;
        if (selector === '') {
          this.$el.bind(eventName, method);
        } else {
          this.$el.delegate(selector, eventName, method);
        }
      }
    },
             		           
                               
                            
                                
               
Clears all callbacks previously bound to the view with delegateEvents.
You usually don't need to use this, but may wish to if you have multiple
Backbone views attached to the same DOM element.
             		                            
    undelegateEvents: function() {
      this.$el.unbind('.delegateEvents' + this.cid);
    },
             		           
                               
                            
                                
               
Performs the initial configuration of a View with a set of options.
Keys with special meaning (model, collection, id, className), are
attached directly to the view.
             		                            
    _configure: function(options) {
      if (this.options) options = _.extend({}, this.options, options);
      for (var i = 0, l = viewOptions.length; i < l; i++) {
        var attr = viewOptions[i];
        if (options[attr]) this[attr] = options[attr];
      }
      this.options = options;
    },
             		           
                               
                            
                                
               
Ensure that the View has a DOM element to render into.
If this.el is a string, pass it through $(), take the first
matching element, and re-assign it to el. Otherwise, create
an element from the id, className and tagName properties.
             		                            
    _ensureElement: function() {
      if (!this.el) {
        var attrs = getValue(this, 'attributes') || {};
        if (this.id) attrs.id = this.id;
        if (this.className) attrs['class'] = this.className;
        this.setElement(this.make(this.tagName, attrs), false);
      } else {
        this.setElement(this.el, false);
      }
    }

  });
             		           
                               
                            
                                
               
The self-propagating extend function that Backbone classes use.
             		                            
  var extend = function (protoProps, classProps) {
    var child = inherits(this, protoProps, classProps);
    child.extend = this.extend;
    return child;
  };
             		           
                               
                            
                                
               
Set up inheritance for the model, collection, and view.
             		                            
  Model.extend = Collection.extend = Router.extend = View.extend = extend;
             		           
                               
                            
                                
               
Backbone.sync
             		                            
             		           
                               
                            
                                
               
Map from CRUD to HTTP for our default Backbone.sync implementation.
             		                            
  var methodMap = {
    'create': 'POST',
    'update': 'PUT',
    'delete': 'DELETE',
    'read':   'GET'
  };
             		           
                               
                            
                                
               
Override this function to change the manner in which Backbone persists
models to the server. You will be passed the type of request, and the
model in question. By default, makes a RESTful Ajax request
to the model's url(). Some possible customizations could be:



    

  • Use setTimeout to batch rapid-fire updates into a single request.
    • 

  • Send up the models as XML instead of JSON.
    • 

  • Persist models via WebSockets instead of Ajax.
    • 




Turn on Backbone.emulateHTTP in order to send PUT and DELETE requests
as POST, with a _method parameter containing the true HTTP method,
as well as all requests with the body as application/x-www-form-urlencoded
instead of application/json with the model in a param named model.
Useful when interfacing with server-side languages like PHP that make
it difficult to read the body of PUT requests.
             		                            
  Backbone.sync = function(method, model, options) {
    var type = methodMap[method];
             		           
                               
                            
                                
               
Default options, unless specified.
             		                            
    options || (options = {});
             		           
                               
                            
                                
               
Default JSON-request options.
             		                            
    var params = {type: type, dataType: 'json'};
             		           
                               
                            
                                
               
Ensure that we have a URL.
             		                            
    if (!options.url) {
      params.url = getValue(model, 'url') || urlError();
    }
             		           
                               
                            
                                
               
Ensure that we have the appropriate request data.
             		                            
    if (!options.data && model && (method == 'create' || method == 'update')) {
      params.contentType = 'application/json';
      params.data = JSON.stringify(model.toJSON());
    }
             		           
                               
                            
                                
               
For older servers, emulate JSON by encoding the request into an HTML-form.
             		                            
    if (Backbone.emulateJSON) {
      params.contentType = 'application/x-www-form-urlencoded';
      params.data = params.data ? {model: params.data} : {};
    }
             		           
                               
                            
                                
               
For older servers, emulate HTTP by mimicking the HTTP method with _method
And an X-HTTP-Method-Override header.
             		                            
    if (Backbone.emulateHTTP) {
      if (type === 'PUT' || type === 'DELETE') {
        if (Backbone.emulateJSON) params.data._method = type;
        params.type = 'POST';
        params.beforeSend = function(xhr) {
          xhr.setRequestHeader('X-HTTP-Method-Override', type);
        };
      }
    }
             		           
                               
                            
                                
               
Don't process data on a non-GET request.
             		                            
    if (params.type !== 'GET' && !Backbone.emulateJSON) {
      params.processData = false;
    }
             		           
                               
                            
                                
               
Make the request, allowing the user to override any Ajax options.
             		                            
    return $.ajax(_.extend(params, options));
  };
             		           
                               
                            
                                
               
Wrap an optional error callback with a fallback error event.
             		                            
  Backbone.wrapError = function(onError, originalModel, options) {
    return function(model, resp) {
      resp = model === originalModel ? resp : model;
      if (onError) {
        onError(originalModel, resp, options);
      } else {
        originalModel.trigger('error', originalModel, resp, options);
      }
    };
  };
             		           
                               
                            
                                
               
Helpers
             		                            
             		           
                               
                            
                                
               
Shared empty constructor function to aid in prototype-chain creation.
             		                            
  var ctor = function(){};
             		           
                               
                            
                                
               
Helper function to correctly set up the prototype chain, for subclasses.
Similar to goog.inherits, but uses a hash of prototype properties and
class properties to be extended.
             		                            
  var inherits = function(parent, protoProps, staticProps) {
    var child;
             		           
                               
                            
                                
               
The constructor function for the new subclass is either defined by you
(the "constructor" property in your extend definition), or defaulted
by us to simply call the parent's constructor.
             		                            
    if (protoProps && protoProps.hasOwnProperty('constructor')) {
      child = protoProps.constructor;
    } else {
      child = function(){ parent.apply(this, arguments); };
    }
             		           
                               
                            
                                
               
Inherit class (static) properties from parent.
             		                            
    _.extend(child, parent);
             		           
                               
                            
                                
               
Set the prototype chain to inherit from parent, without calling
parent's constructor function.
             		                            
    ctor.prototype = parent.prototype;
    child.prototype = new ctor();
             		           
                               
                            
                                
               
Add prototype properties (instance properties) to the subclass,
if supplied.
             		                            
    if (protoProps) _.extend(child.prototype, protoProps);
             		           
                               
                            
                                
               
Add static properties to the constructor function, if supplied.
             		                            
    if (staticProps) _.extend(child, staticProps);
             		           
                               
                            
                                
               
Correctly set child's prototype.constructor.
             		                            
    child.prototype.constructor = child;
             		           
                               
                            
                                
               
Set a convenience property in case the parent's prototype is needed later.
             		                            
    child.__super__ = parent.prototype;

    return child;
  };
             		           
                               
                            
                                
               
Helper function to get a value from a Backbone object as a property
or as a function.
             		                            
  var getValue = function(object, prop) {
    if (!(object && object[prop])) return null;
    return _.isFunction(object[prop]) ? object[prop]() : object[prop];
  };
             		           
                               
                            
                                
               
Throw an error when a URL is needed, and none is supplied.
             		                            
  var urlError = function() {
    throw new Error('A "url" property or function must be specified');
  };

}).call(this);