BackboneJS - Collection Length


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Description

It is a property that counts the number of models in the collection.

Syntax

collection.length

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">

         //'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>

Output

Let us carry out the following steps to see how the above code works −

  • Save the above code in the length.htm file.

  • Open this HTML file in a browser.

backbonejs_collection.htm
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