Socket IO Example

Question

I am trying to use socket io so I can dynamically update data on a site:

Edit: Updated Code

In app.js:

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

var routes = require('./routes/index');
app.use('/', routes);

var server = require('http').createServer(app);
var io = require('socket.io')(server);

  io.on('connection', function(socket){
  socket.emit('news', {hello: 'world'}); 
  socket.on('my other event', function (data) {
  console.log(data);
  });
});

server.listen(app.get('port'), function(){
  console.log('Express listening on port ' + app.get('port'));
});

In index.ejs:

<script src="/socket.io/socket.io.js"></script>
<script>
var socket = io.connect('http://localhost:80');
socket.on('news', function(data) {
  socket.emit('my other event', {my: 'data'});
});
</script>

The page loads correctly, however the socketio script does nothing. I have tried to make the code as simple as possible.

Express listening on port 80 outputs to console fine.

in www.

#!/usr/bin/env node

/**
 * Module dependencies.
 */

var app = require('../app');
var debug = require('debug')('untitled:server');
var http = require('http');

/**
 * Get port from environment and store in Express.
 */

var port = normalizePort(process.env.PORT || '3000');
app.set('port', port);

/**
 * Create HTTP server.
 */

var server = require('http').Server(app);

//var io = require('socket.io')(server);

/**
 * Listen on provided port, on all network interfaces.
 */

server.listen(port);
server.on('error', onError);
server.on('listening', onListening);

/**
 * Normalize a port into a number, string, or false.
 */

function normalizePort(val) {
  var port = parseInt(val, 10);

  if (isNaN(port)) {
    // named pipe
    return val;
  }

  if (port >= 0) {
    // port number
    return port;
  }

  return false;
}

/**
 * Event listener for HTTP server "error" event.
 */

function onError(error) {
  if (error.syscall !== 'listen') {
    throw error;
  }

  var bind = typeof port === 'string'
    ? 'Pipe ' + port
    : 'Port ' + port;

  // handle specific listen errors with friendly messages
  switch (error.code) {
    case 'EACCES':
      console.error(bind + ' requires elevated privileges');
      process.exit(1);
      break;
    case 'EADDRINUSE':
      console.error(bind + ' is already in use');
      process.exit(1);
      break;
    default:
      throw error;
  }
}

/**
 * Event listener for HTTP server "listening" event.
 */

function onListening() {
  var addr = server.address();
  var bind = typeof addr === 'string'
    ? 'pipe ' + addr
    : 'port ' + addr.port;
  debug('Listening on ' + bind);
}

score 2 · Answer 1 · 2016-04-09T02:58:17.583

2

Not quite sure by what you mean as "socket script doesn't do anything" as you aren't really doing anything on the client side! From the code posted anyway.

EDIT:

This code works for me on the client and server.

server.js

var express = require('express');
var app = express();
var http = require('http').Server(app);
var io = require('socket.io')(http);

app.set('view engine', 'jade');
app.set('views', './views');

app.get('/', function (req, res) {
  res.render('index');
});

io.on('connection', function (socket) {
  console.log('connected via server');
});

http.listen(3000, function () {
  console.log('app listening on port 3000');
});

index.jade (you can use ejs or html)

html
    head
        script(src="/socket.io/socket.io.js")
        script.
            var socket = io.connect();
            socket.on('connect', function() {
                console.log('greetings from client');
            });
    body
        h1 hello world

You can also try serving up the socket.io-client package yourself manually.

edited Apr 09 '16 at 02:58

answered Apr 09 '16 at 01:28

Sorry, I have tried this. It basically doesnt do anything (doesnt print 'greetings from client'). – user1212520 Apr 09 '16 at 01:31
Strange.. Have you tried emitting an event from the server and catching it on the client? – Apr 09 '16 at 01:36
You don't have to create a route for the client version of socket.io because the socket.io library does that automatically and it is built into the server version of socket.io. So, I don't see what answer you're actually providing here. – jfriend00 Apr 09 '16 at 02:40
@jfriend00 You are right, I edited it, and it still works. The reason why I mentioned serving it up manually is because they already tried it and it doesn't work. Was just a suggestion to try and get something on screen. – Apr 09 '16 at 02:59

hankchiutw · Answer 2 · 2016-04-09T03:39:35.277

Check if app.get('port') works correctly and how do you serve the static site.

I tried to set it explicitly and works:

app.js

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

app.set('view engine', 'ejs');
app.set('views', './views');

app.get('/', function (req, res) {
  res.render('index');
}); 

var server = require('http').createServer(app);
var io = require('socket.io')(server);

io.on('connection', function(socket){
  socket.emit('news', {hello: 'world'}); 
  socket.on('my other event', function (data) {
  console.log(data);
  }); 
}); 

server.listen(3100, function(){
  console.log('Express listening on port ' + 3100);
});

index.ejs

<script src="/socket.io/socket.io.js"></script>
<script>
var socket = io.connect('http://localhost:3100');
socket.on('news', function(data) {
  socket.emit('my other event', {my: 'data'});
});
</script>

Or use <script src="http://localhost:3100/socket.io/socket.io.js"></script> if the static site is hosted in elsewhere.

My homepage is on port 80. I am not sure what port to use. If I use app.get('port') it outputs 80, but if I manually put 80 in I get an error saying it is already in use? I am not sure if it is to do with the www file? — user1212520, Apr 09 '16 at 11:18

score 1 · Answer 3 · edited May 23 '17 at 12:22

1

Finally solved it:

Using socket.io in Express 4 and express-generator's /bin/www

I had to make some changes for express 4.0

edited May 23 '17 at 12:22

Community

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answered Apr 09 '16 at 12:08

user1212520

501
1
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1

A proper answer would show what changes you actually had to make. – jfriend00 Apr 09 '16 at 16:04

Socket IO Example

3 Answers3