Backbone.Router mixin to bind optional route mappings. This would be useful for user-only or admin-only routes that would 404 otherwise.

optroutes.mixin.js

/**
 * Usage:
 * var MyRouter = Backbone.Router.extend(_.extend({}, OptionalRouteMixin, {
 *   userRoutes: {
 *     '/profile': 'profile'
 *   },
 *   initialize: function(options) {
 *     this._bindOptRoutes(this.userRoutes);
 *   }
 * }));
 */
var OptionalRouteMixin = {
  // The following is borrowed from Backbone.Router._bindRoutes.
  _bindOptRoutes: function(optRoutes) {
    if (!optRoutes) return;
    var route, routes = _.keys(optRoutes);
    while ((route = routes.pop()) != null) {
      this.route(route, optRoutes[route]);
    }
  }
};

Opened an issue with BackboneJS to support this directly.