Backbone.js collection.at()

The Backbone.js collection at method is used to retrieve model from a collection by using specified index.

Syntax:

Parameter explanation:

index: It species an index position where model can be retrieved from a collection.

Let's take an example.

See this example:

<!DOCTYPE html>
   <head>
      <title>At Collection Example</title>
         <script src="https://code.jquery.com/jquery-2.1.3.min.js" type="text/javascript"></script>
         <script src="https://cdnjs.cloudflare.com/ajax/libs/underscore.js/1.8.2/underscore-min.js" type="text/javascript"></script>
         <script src="https://cdnjs.cloudflare.com/ajax/libs/backbone.js/1.1.2/backbone-min.js" type="text/javascript"></script>
   </head>
   <body>
      <script type="text/javascript">
         //The model name is 'Player' and contains default values
         var Player = Backbone.Model.extend({
            defaults: {
               id:"",
               name: ""
            }
         });

         //'PlayersCollection' is an instance of the collection
         var PlayersCollection = Backbone.Collection.extend({
            model: Player  //model 'Player' is specified by using model property
         });
         var player1 = new Player({id:1, name: "Dravid" });
         var player2 = new Player({id:2, name: "Ganguly"});

           //The add() method adds the models 'player1' and 'player2' to the collection instance 'mycollection'
         var mycollection = new PlayersCollection();
         mycollection.add([player1,player2]);
         document.write('<b>Players added are :</b> ' + JSON.stringify(mycollection.toJSON()));
         var player3 = new Player({id:3, name: "Sehwag" });

         //Here, adding the model 'player3' at 0th index of the collection
         mycollection.add(player3,{at:0});

         //display all the models added. player3 will be added at the 0th position
         document.write('<br><b>Now the new list of players is :</b> ' + JSON.stringify(mycollection.toJSON()));
      </script>
   </body>
</html>

Test it Now

Output:

Save the above code in at.html file and open this file in a new browser.