There are cases when we have a mixed set of data coming from the server and we need to put the complete data in a single collection. For example, assume that the server is sending the complete employee details of a company. Now, there are different types of employees—developers, managers, designers, and so on, and you want to have different model types for each of these. How is the collection supposed to hold all types of models together? Here is an example with which you can get the desired functionality:

var Employee = Backbone.Model.extend();
var Developer = Employee.extend();
var Manager = Employee.extend();

var Employees = Backbone.Collection.extend({
  url: 'employees.json',
  model: function (attrs, options) {
    // For each data, check the attribute type
    switch (attrs.type) {
      case "Developer":
        return new Developer(attrs, options);
        break;

      case "Manager":
        return new Manager(attrs, options...