How the Express Router function works

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To use a middleware in Express, I do as the code below:

var express = require('express');
var app = express();

app.use('/', function(req, res, next) { 
    console.log('Middleware!');
});

However, I realized that it is also possible to do this:

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

var app = express();

router.get('/', function(req, res, next) {
    res.send('Index!');
});

router.get('/teste', function(req, res, next) {
    res.send('Teste!');
});

app.use('/', router);

How does the Router function work? What does it do under the cloths?

javascript express node.js

1 answer

1

express. Router() is a Nodejs route manager/handler. It serves to create routes in a modularized way, thus making it possible to create a separate file of route manipulation.

For example, create a directory called "Rotes" and create an "indexRotes.js" file. Inside this file you will use Router() to create a route structures that will soon be exported.

indexRotas.js

const express = require('express')
const router = express.Router() //chamei de router mas poderia ser qualquer outro nome

router.use((req, res, next) => {...})

router.get('/', (req, res) => {...})

router.get('/home', (req, res) => {...})

router.get('/login', (req, res) => {...})
router.post('/login', (req, res) => {...})

//404
router.use((req, res) => {
    res.send('404: Page not found')
})

module.exports = router

Notice I used the Router() to create several routes and at the end I exported it. Now in the archive apps js. I can care you.

app js.

//IMPORTS EXTERNAL   
const express = require('express')
const app = express()

//IMPORTS INTERNAL
const routes = require('./rotes/indexRotes') //importando o roteador

//SERVER CONFIG
app.use(...)
app.use(...)
app.listen(...)

//ROUTES
app.use('/', routes)

Okay, now you have a separate file that specifically takes care of your routes, with direct to middleware and more, in a large application can contain hundreds of routes, so it is more interesting a modular router that takes care of just that.

Tip: recommend you declare the next only when using it, so keep the code cleaner and no unnecessary information.

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