BackboneJS - Collection Length

更新于 2025/12/3 22:17:00

描述

这是一个计算集合中模型数量的属性。

语法

collection.length

示例

<!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">

        //'Cities' 是一个模型，包含模型的默认值
        var Cities = Backbone.Model.extend ({
            defaults: {
                city: "Hyderabad"
            }
        });
        
        //'CityCollection' 是集合的一个实例
        var CityCollection = Backbone.Collection.extend ({
            model: Cities //模型 'Cities' 通过使用模型属性指定
        });
        
        //add() 方法将模型 'city1'、'city2' 和 'city3' 添加到集合实例 'mycollection'
        var city1 = new Cities({city: "Banglore"});
        var city2 = new Cities({city: "Delhi"});
        var city3 = new Cities({city: "Mumbai"});
        var mycollection = new CityCollection();
        mycollection.add([city1,city2,city3]);
        document.write('集合中的模型数量：' + mycollection.length);
      </script>
      
   </body>
</html>