at

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小牛编辑

129浏览

2023-12-01

描述 (Description)

它用于通过使用指定的索引从集合中检索模型。

语法 (Syntax)

collection.at(index)

参数 (Parameters)

index - 这是一个索引位置，我们可以从集合中获取模型。

例子 (Example)

<!DOCTYPE html>
<html>
   <head>
      <title>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: "dhoni" });
         var player2 = new Player({id:2, name: "raina"});
         //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: "yuvraj" });
         //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>