backbone.js集合length backbone.js集合length|Backbone.js教程

长度是集合的属性。它用于计算集合包含的模型数量。
句法：

collection.length

让我们举个例子。
请参阅以下示例：

< !DOCTYPE html> < head> < title>Length Collection Example< /title> < script src="http://img.readke.com/220416/052H4HX-0.jpg" type="text/javascript">< /script> < script src="http://img.readke.com/220416/052H42553-1.jpg" type="text/javascript">< /script> < script src="http://img.readke.com/220416/052H461S-2.jpg" type="text/javascript">< /script> < /head> < body> < script type="text/javascript"> //'Cities' is a model and contains defualt value for the model var Cities = Backbone.Model.extend({ defaults: { city: "Hyderabad" } }); //'CityCollection' is an instance of the collection var CityCollection = Backbone.Collection.extend({ model: Cities//model 'Cities' is specified by using model property }); //The add() method adds the models 'city1', 'city2' and 'city3' to the collection instance '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('Number of models in collection : ' + mycollection.length); < /script> < /body> < /html>

输出：
【backbone.js集合length】将以上代码保存在length.html文件中，然后在新的浏览器中打开该文件。