pluck

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小牛编辑

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2023-12-01

描述 (Description)

它从集合中的每个模型中检索属性。

语法 (Syntax)

collection.pluck(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">
         var LangNames  = Backbone.Model;          //'LangNames' is a model name
         var langauges = new Backbone.Collection;  //'langauges' is a collection instance
         //The collection instance used with comparator() method to compare the items and display them 
         //in descending order
         langauges.comparator = function(value1, value2) {
            //The comparator returns -1, when the first model should display before the second model
            if (value1.get('name') > value2.get('name')) return -1;
            //It returns -1, when the first model should display after the second model
            if (value2.get('name') > value1.get('name')) return 1;
            return 0;
         };
         langauges.add(new LangNames({name: "Java"}));
         langauges.add(new LangNames({name: "PHP"}));
         langauges.add(new LangNames({name: "HTML"}));
         //The pluck() method returns an attribute, by using "name" attribute from the model in the collection
         document.write("Attributes returned on pluck('name'): ",langauges.pluck('name'));
      </script>
   </body>
</html>