Backbone Error 404

e404.js

window.APP = Backbone.Router.extend({

  initialize: function(){
    this.route(/.*?/, "e404");
    this.route(/^$/, 'mainPage');
    //Some other routes
 },
  
  e404: function(){
    console.log("Error 404!");
  },

  mainPage: function(){
    console.log("Main page!");
  }

});