NodeJS + ExpressJS: What is routes/index.js and its purpose?

Question

What is the purpose of this file?

Is this where 'all' the get and post calls get instantiated?

If so, wouldn't this be a very huge file when working with large scale projects?

I've tried calling a post, /authenticateLogin, from another file other than routes/index.js, but it fails to work, resulting in a 404 error.

routes/login.js

var express = require('express');
var router = express.Router();

router.get('/', function(req, res) {
    res.render('login');
});

router.post('/authenticateLogin', function(req, res){
    console.log("Authenticating 2!");
    res.send('number two!');
});

module.exports = router;

But it works perfectly when I put it in the index.js file.

routes/index.js

var express = require('express');
var router  = express.Router();

router.get('/', function(req, res) {
    res.render('index', { title: 'Home' });
});

router.post('/authenticateLogin', function(req, res){
    console.log("Authenticating 1!");
    res.send('number one!');
});

module.exports = router;

views/login.jade

extends layout

block content
h1 Login 

form(method='post' action='/authenticateLogin')
    input(type='text' placeholder='username' name='username')
    input(type='password' placeholder='password' name='password')

    input(type='submit')

Answer 1

That's where you actually load the framework and define the routes.

Answer 2

You can spread your routes into several files.

Actually, Dominic Barnes already answered your question.

Answer 3

In login.js, you can define your routes and to make these routes work, you need to import this file to your index.js.

So in this way if you are working on a large scale project, you can just follow this modular approach and define routes in different files and include all these files in index.js file.