socket.io & express: 404 not found

Question

My app.js

const express = require(\'express\'),
      morgan = require(\'morgan\'),
      bodyParser = require(\'body-parser\'),
      path = require(\'path\'),
         


        

Answer 1

If you're going to do this:

server = require('http').createServer(app),

Then, you can't do:

app.listen(PORT, ...);

because app.listen() will create a new and different server and socket.io will not be associated with that one.

Instead, you need to do:

server.listen(PORT, ...)

using the server value from app.js. And, if you want to require() in the server from app.js, you also need to export it from app.js (something else I don't see your code doing).

---

For reference, the code for app.listen(), does this:

app.listen = function listen() {
  var server = http.createServer(this);
  return server.listen.apply(server, arguments);
};

You can see how it creates a different server than the one you passed to socket.io. Thus the one you passed to socket.io is never started and thus socket.io does not work.