Express node.js - understanding routing

Question

I have this about.js route and it works fine but I don't understand how / in router.get() would work while /about wouldn't?

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

router.get('/', function(req, res, next) {
  res.render('about', { title: 'About' });
});

module.exports = router;

----------------- UPDATE ----------------------

It's basically what I got out of the box after installing express.js except the about lines.

I expected router.get('/about' ...) in about.js would work but it threw an error and it worked with / instead and that's what bugs me.

app.js

var express = require('express');
var path = require('path');
var favicon = require('serve-favicon');
var logger = require('morgan');
var cookieParser = require('cookie-parser');
var bodyParser = require('body-parser');

var routes = require('./routes/index');
var users = require('./routes/users');
var about = require('./routes/about');

var app = express();

// view engine setup
app.set('views', path.join(__dirname, 'views'));
app.set('view engine', 'ejs');

// uncomment after placing your favicon in /public
//app.use(favicon(path.join(__dirname, 'public', 'favicon.ico')));
app.use(logger('dev'));
app.use(bodyParser.json());
app.use(bodyParser.urlencoded({ extended: false }));
app.use(cookieParser());
app.use(express.static(path.join(__dirname, 'public')));

app.use('/', routes);
app.use('/users', users);
app.use('/about', about);

// catch 404 and forward to error handler
app.use(function(req, res, next) {
  var err = new Error('Not Found');
  err.status = 404;
  next(err);
});

// error handlers

// development error handler
// will print stacktrace
if (app.get('env') === 'development') {
  app.use(function(err, req, res, next) {
    res.status(err.status || 500);
    res.render('error', {
      message: err.message,
      error: err
    });
  });
}

// production error handler
// no stacktraces leaked to user
app.use(function(err, req, res, next) {
  res.status(err.status || 500);
  res.render('error', {
    message: err.message,
    error: {}
  });
});


module.exports = app;

I've edited my question slightly. Basically I understand how / works for index.js but not for other routes. — Seong Lee
– Seong Lee, Commented Sep 29, 2015 at 13:17
What do you mean by /about not working? If you want the function to run when you visit http://yourpage.tld/about, you of course need a route for that: router.get('/about', function(req, res, next){ /* your code */});. — ROAL
– ROAL, Commented Sep 29, 2015 at 13:23
That's what I thought but I get error when I do that. Instead / would work when visiting http://example.com/about — Seong Lee
– Seong Lee, Commented Sep 29, 2015 at 13:27

Felipe Skinner · Accepted Answer · 2015-09-29 14:05:52Z

The problem

When you define a route on your app.js as you did with app.use('/about', about);. You are already telling express that you expect requests to hit http://yourserver/about route.

If you try to define /about again inside your about.js with:

router.get('/', function(req, res, next) {
  res.render('about', { title: 'About' });
});

What you're doing is tellig the Express that you will hit a /about inside your firstly declared /about. So it will expect requests on this route: http://yourserver/about/about

The solution

It's actually what you're using. Define a root route inside your about.js as:

router.get('/', function(req, res, next) {
  res.render('about', { title: 'About' });
});

This way your app will be:

Modular since you're using different files for different routes (about.js, users.js)
Easier to read
With simplier routes inside each file, since you don't need to type /about everytime you wish to create a new route.

If you wish a http://yourserver/about/help simply add a handler inside your route file about.js as here:

router.get('/help', function(req, res, next) {
  res.render('help', { title: 'Help' });
});

Manish Jangir · Accepted Answer · 2015-09-29 13:25:49Z

0

If you want the route /about work then you have to create another route:

router.get('/about', function(req, res, next) {
  res.render('about-page', { title: 'About' });
});

because / will only work for the home page.

answered Sep 29, 2015 at 13:25

Manish Jangir

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