Casting Backbone Collection object to its original type

Question

I use backbone js to add custom elements to a backbone js Collection . I need to cast it back to its original type below is the

var Text = function () {

};

var Radio = function () {

};

function myfunction() {
    var collection = new Backbone.Collection();
    var t = new Text();
    var r = new Radio();
    collection.add(t);
    collection.add(r);

    alert(t instanceof Text);
    alert(collection.at(0) instanceof Text);

}

The statement alert(t instanceof Text); returns true where as the statement

alert(collection.at(0) instanceof Text); returns false .

Is there any way i could cast it to its original type ?

Answer 1

You can't.

• collection.add(t) is equivalent to collection.add(new Backbone.Model(t)) when t does not inherit Backbone.Model¹

• Backbone.Model's constructor copies the attributes of t into the new object via Model.set but does not keep any other information on the source object²

If you can, extend Backbone.Model to build Text and Radio

var Text = Backbone.Model.extend({

});

If not, you will have to add additional information in your attributes to identify the correct prototypes.

---

¹ Annotated source code, Collection._prepareModel
² Annotated source code, Model.set