In Backbone.js, by default, collections are not explicitly sorted. We can sort the collections by defining a comparator on the collection object. By defining a comparator, a collection is sorted whenever a model is added or the "sort()" method is invoked on a collection :
Example :
var Fruits = Backbone.Collection.extend({
comparator: function(a, b) { /* .. */ }
})
// Or
var Fruits = Backbone.Collection.extend({})
var fruits = new Fruits()
fruits.comparator = function(a, b) { /* .. */ }
The comparator property can be a function with one argument or two arguments (similarly used in "sort"), or a string identifying the attribute by name to sort on.
When an attribute of a model in a collection changes, the collection doesn't sort itself. In this case, the sort must be invoked explicitly to update the order of models in the collection.
