Throw errors when binding null events in Backbone.

backbone.eventSafety.js

/*global Backbone: true, _:true */
(function() {
  "use strict";
  /**
   * Backbone.eventSafety
   *
   * Simple plugin that throws an error when Backbone.Events.on & Backbone.Events.once are called
   * without a callback. Because you might be counting on that and accidentally pass it undefined
   * because of a scoping error.
   * Why Backbone doesn't do that, only God and @jashkenas knows.
   *
   * @author ssafejava
   */
  
  var oldOn = Backbone.Events.on, oldOnce = Backbone.Events.once;

  var override = {
    on: function(name, callback, context){
      if (!callback) throw new Error("A callback must be provided to on() when binding an event!");
      return oldOn.apply(this, arguments);
    },
    once: function(name, callback, context){
      if (!callback) throw new Error("A callback must be provided to once() when binding an event!");
      return oldOnce.apply(this, arguments);
    }
  };
  // Backward compatibility
  override.bind = override.on;

  _.extend(Backbone, override);
  _.extend(Backbone.Collection.prototype, override);
  _.extend(Backbone.Events, override);
  _.extend(Backbone.History.prototype, override);
  _.extend(Backbone.Model.prototype, override);
  _.extend(Backbone.Router.prototype, override);
  _.extend(Backbone.View.prototype, override);
}).call(this);