Showing posts with label socket-io. Show all posts
Showing posts with label socket-io. Show all posts

Wednesday, November 20, 2019

Install Express.js web application framework for Node.js with SockeIO

Express.js is a web application framework for Node.js. FIrst install nodejs and npm.
You can install express.js using npm. The following command will install latest version of express.js globally on your machine so that every Node.js application on your machine can use it. Just run the following command

npm install -g express
Now create a directory named Node1 and navigate to the directory from command prompt (for windows) and run the following command will install nodejs express web framework to the following directory.

First run npm init to initialize a probject.

Then run following command to install express and socketio respectively.

npm install --save express

npm install --save socket.io
We then run npm install to get all the dependencies that are needed to run the app. To test the empty application, run node main.js then navigate your browser to http://127.0.0.1:8081. Main.js is as below:
let app = require('express')();
let http = require('http').Server(app);
let io = require('socket.io')(http);

// Send socket initialization scripts to the client
app.get('/', function(req, res){
    res.send(`
<script src="/socket.io/socket.io.js"></script>
<script>
    let socket = io();
    socket.on('text', (txt) => {
  console.log(txt);
        let textp = document.createElement("h1");
        let t = document.createTextNode(txt);
        textp.appendChild(t);                                            
        document.body.appendChild(textp);
    });
</script>`);
});

// Respond to socket connections with a Hello World text
io.on('connection', (socket) => {
    console.log('User connected');
    io.emit('text', 'Hello, World!');
});

// Run our socket-enabled server
http.listen(8081, function() {
    console.log('listening on *:8081');
});
io.on('connect', onConnect);

function onConnect(socket){

  // sending to the client
  socket.emit('hello', 'can you hear me?', 1, 2, 'abc');

  // sending to all clients except sender
  socket.broadcast.emit('broadcast', 'hello friends!');

  // sending to all clients in 'game' room except sender
  socket.to('game').emit('nice game', "let's play a game");

  // sending to all clients in 'game1' and/or in 'game2' room, except sender
  socket.to('game1').to('game2').emit('nice game', "let's play a game (too)");

  // sending to all clients in 'game' room, including sender
  io.in('game').emit('big-announcement', 'the game will start soon');

  // sending to all clients in namespace 'myNamespace', including sender
  io.of('myNamespace').emit('bigger-announcement', 'the tournament will start soon');

  // sending to a specific room in a specific namespace, including sender
  io.of('myNamespace').to('room').emit('event', 'message');

  // sending to individual socketid (private message)
  io.to(`${socketId}`).emit('hey', 'I just met you');

  // WARNING: `socket.to(socket.id).emit()` will NOT work, as it will send to everyone in the room
  // named `socket.id` but the sender. Please use the classic `socket.emit()` instead.

  // sending with acknowledgement
  socket.emit('question', 'do you think so?', function (answer) {});

  // sending without compression
  socket.compress(false).emit('uncompressed', "that's rough");

  // sending a message that might be dropped if the client is not ready to receive messages
  socket.volatile.emit('maybe', 'do you really need it?');

  // specifying whether the data to send has binary data
  socket.binary(false).emit('what', 'I have no binaries!');

  // sending to all clients on this node (when using multiple nodes)
  io.local.emit('hi', 'my lovely babies');

  // sending to all connected clients
  io.emit('an event sent to all connected clients');

};