Express js和socket io端口3000已经

Question

I am trying to follow tutorial on how to use socket.io with express.js framework and node.js.

Every tutorial I am following suggested I use the following lines to establish a connection in app.js

var server = require('http').createServer(app);
var io = require('socket.io')(server);
server.listen(3000);


io.on('connection', function(client) {
   console.log('Client connected...');

   client.on('join', function(data) {
     console.log(data);
  });
})

This worked if I use port other than 3000 which I am having to run my application on http://localhost:3000/ . I get the error that Port 3000 already in use.

After debugging and looking at the code I think I have an idea of why is this happening. In ./bin/www.js file (created automatically by express js) we have the following lines:

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

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

but I am not sure how to reuse this created server with same port in my app.js. I am totally new to node.js. How do I setup socket io on the express framework the right way?

Answer 1

hello there please put your server.listen after socket connection like this

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

io.on('connection', function(client) {
   console.log('Client connected...');

   client.on('join', function(data) {
     console.log(data);
  });
})
server.listen(3000);

I hope this would work.Thanks

Answer 2

In order to kill any existing node process, you can run killall node command in your shell.

Remove this line from your code, which is hardcoding the port number -

server.listen(3000);

and add something like this instead -

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

app.listen(app.get('port'));

So your code would look something like -

var server = require('http').createServer(app);
var io = require('socket.io')(server);
// server.listen(3000);
app.set('port', process.env.PORT || 3000);


io.on('connection', function(client) {
   console.log('Client connected...');

   client.on('join', function(data) {
     console.log(data);
  });
});

server.listen(app.get('port'));

Now when your run your app again, it would boot on port 3000 by default or you can pass an environment variable (PORT) while starting the server like this to run on other ports.

$ PORT=8080 node app.js