Backbone: to indicate Backbone fetch progress , to override a method @ Collection, Model . //patching the fetch method on Collection.prototype to emit a fetch event.

example.js

Repos.Views.List = Backbone.View.extend({
  initialize: function() {
    // Display a loading indication whenever the Collection is fetching.
    this.collection.on("fetch", function() {
      this.html("<img src='/assets/img/spinner.gif'>");
    }, this);

    // Automatically re-render whenever the Collection is populated.
    this.collection.on("reset", this.render, this);
  }
});

patch.js

// Patch Model and Collection.
_.each(["Model", "Collection"], function(name) {
  // Cache Backbone constructor.
  var ctor = Backbone[name];
  // Cache original fetch.
  var fetch = ctor.prototype.fetch;

  // Override the fetch method to emit a fetch event.
  ctor.prototype.fetch = function() {
    // Trigger the fetch event on the instance.
    this.trigger("fetch", this);

    // Pass through to original fetch.
    return fetch.apply(this, arguments);
  };
});

For future readers, there's now a request event which replaces the fetch event here. And there's a sync event which is triggered when a model or collection has been successfully synced with the server.