How to sort collections in backboneJs - backbone.js

Question

im learning BackboneJs using the documentation and a book called "Beginning backbone".
But I have been stuck at the sorting collections part for hours.
Also tried to research but I find the results complicated =/
I know I have to use the comparator, as shown in the documentation but I don't understand how to apply it to the current code syntax-wise
http://backbonejs.org/#Collection-comparator
var Book = Backbone.Model.extend({
defaults:
{
title: "default title",
author: "default author",
pages: 20
},
comparator: function(item)
{
//sort by title
return item.get('title');
}
});
var book1 = new Book({ title:"Book of wonders",author:"author1",pages:1 });
var book2 = new Book({ title:"Zelda",author:"author2",pages:2 });
var book3 = new Book({ title: "Drake's out", author: "author3",pages:3});
var book4 = new Book({ title: "AutoCad",author: "author4",pages: 4});
var Library = Backbone.Collection.extend({
model: Book
});
var library = new Library([book1,book2]);
library.add([book3,book4]);
library.forEach(function(model){
console.log('Book is called '+model.get("title"));
});
console.log('Library contains '+library.length+' books');

Answer 1

This is a working solution, it will sort everything by title.
to sort it by anything else just change the parameter of the get function inside the comparator function
var Book = Backbone.Model.extend({
defaults:
{
title: "default title",
author: "default author",
pages: 20
}
});
var book1 = new Book({ title:"Book of wonders",author:"author1",pages:1 });
var book2 = new Book({ title:"Zelda",author:"author2",pages:2 });
var book3 = new Book({ title: "Drake's out", author: "author3",pages:3});
var book4 = new Book({ title: "AutoCad",author: "author4",pages: 4});
var Library = Backbone.Collection.extend({
model: Book,
initialize: function()
{
console.log("new collection");
},
comparator: function(a,b)
{
//sort by title
return a.get('title') < b.get('title') ? -1 : 1;
}
});
var library = new Library([book1,book2]);
library.add([book3,book4]);
library.sort();
library.forEach(function(model){
console.log('Book is called '+model.get("title"));
});
console.log('Library contains '+library.length+' books');