javascript - Backbone treat model like collection

Question

Since Collections is actually a model, it has attributes and so on, like in this example

var Images = Backbone.Collection.extend({
  url: 'https://api.myjson.com/bins/4v2d8'
});

var View = Backbone.View.extend({
  el: $('.images'), 

  initialize: function(){
    this.listenTo(this.collection, 'sync', this.render, this); // what is this keyword as the last param here?
  },

  render: function(){

    this.collection.each(function(model){
      this.$el.append($('<p>'+model.get('name')+'</>' ));
    }, this);

  }
});

$(function(){

  var images = new View({ collection: new Images() });

  images.collection.fetch();

});

http://jsbin.com/gohedeguto/edit?html,js,output

But why this one doesn't work?

http://jsbin.com/seyoyeqeku/edit?html,js,output

I replaced Collection with Model and passed to the View. I got this.model.each of undefined.

Answer 1

While T-J is right, he doesn't elaborate on why.

A Backbone model has lots of functions to manage an attributes hash, and is often referenced by an id.

A Backbone collection is an array of Backbone model instances. It has some similar and lots of different functions to manage its models array property which is where the model instances are stored.

Some of these functions are proxies to Underscore.js functions.

Model's Underscore methods

• keys
• values
• pairs
• invert
• pick
• omit
• chain
• isEmpty

Collection's Underscore methods

46 in total at the moment, see the list.

---

collection.each(iteratee, [context])

is a proxy to _.each(collection.models, iteratee, [context]).

Backbone's Model do not have a each function because it doesn't really make sense and there are better ways to loop through the attributes of a model.