Step 17 -> 18

17.diff

 var events = _.clone(Backbone.Events);

+var Status = Backbone.Model.extend({
+    url: '/status'
+});
+
 var Statuses = function() {
 };
 Statuses.prototype.add = function(text) {
-    $.ajax({
-        url: '/status',
-        type: 'POST',
-        dataType: 'json',
-        data: { text: text },
-        success: function(data) {
-            events.trigger('status:add', data.text);
-        }
-    });
+    var status = new Status();
+    status.save({ text: text }, {
+        success: function(model, data) {
+            events.trigger('status:add', data.text);
+        }
+    });
 };

 var NewStatusView = Backbone.View.extend({
     initialize: function(options) {
         this.statuses = options.statuses;

         events.on('status:add', this.clearInput, this);

         var add = $.proxy(this.addStatus, this);
         this.$('form').submit(add);
     },

     addStatus: function(e) {
         e.preventDefault();

         this.statuses.add(this.$('textarea').val());
     },

     clearInput: function() {
         this.$('textarea').val('');
     }
 });

 var StatusesView = Backbone.View.extend({
     initialize: function(options) {
         events.on('status:add', this.appendStatus, this);
     },

     appendStatus: function(text) {
         this.$('ul').append('<li>' + text + '</li>');
     }
 });

 $(document).ready(function() {
     var statuses = new Statuses();
     new NewStatusView({ el: $('#new-status'), statuses: statuses });
     new StatusesView({ el: $('#statuses') });
 });