where

优质

小牛编辑

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2023-12-01

描述 (Description)

它用于通过使用集合中的匹配属性来显示模型。

语法 (Syntax)

collection.where(attribute)

参数 (Parameters)

attribute - 它表示已定义模型的属性。

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">
         //'Player' is a model name
         Player = Backbone.Model.extend ({
            name: ""
         });
         //The 'PlayersCollection' is an instance of the collection
         PlayersCollection = Backbone.Collection.extend ({
            model: Player  //The model 'Player' is specified by overriding the "model" property of the collection
         });
         var player1 = new Player({ name: "Dravid" });
         var player2 = new Player({ name: "Raina"});
         var player3 = new Player({ name: "Jadeja"});
         var mycollection = new PlayersCollection();
         //The 'player1','player2' and 'player3' are 3 instances added to the collection by using 'mycollection' instance
         mycollection.add(player1);
         mycollection.add(player2);
         mycollection.add(player3);
         //The where() method returns the model, which contains the name with "Raina" in the collection
         var myteam = mycollection.where({ name: 'Raina' });
         document.write("Total numbers of items that matches given attribute are:", 
            +myteam.length);
      </script>
   </body>
</html>