If I try the following code:
var c = new Backbone.Collection();
c.localStorage = new Backbone.LocalStorage("items");
c.add({title: 'exemple'});
c.toJSON(); // [object]
If I try to see the localStorage.items I can not see anything.
How should I store the data in localStorage?
In order to save your collection in localStorage you need to create a new instance of a model within a collection.
var c = new Backbone.Collection();
c.localStorage = new Backbone.LocalStorage("items");
c.create({title: 'exemple'});
c.toJSON(); // [object]
localStorage.items; // will be defined
What are you trying to do? Backbones localStorage adapter is for saving models to localStorage instead of a REST service. If you try to store some additional value in localStorage you can still use localStorage.setItem("foo", "bar")
