Simple Node.JS WebSocket Server

Now we will write a simple WebSocket server in node.js. When you connect to this server, you will receive a welcome message in response. And also a couple of simple commands will be available for execution.

To do this, you need to install Node.js with the npm package manager, it comes with

Project setup

First, we need to create a directory for the future project

mkdir websocket-server-node
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

Go to the directory

cd websocket-server-node
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

Next, you need to initialize a new project via npm

npm init
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

The installer will ask you to answer a few questions, you can skip them

, WS UTF-8

npm install ws
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

npm install --save-optional utf-8-validate
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

websocket-

. server.js, . , GitHub.

server.js:

websocket

const WebSocket = require('ws');
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

, , WebSocket, WebSocket-.

const wsServer = new WebSocket.Server({port: 9000});
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

HTTP-, WebSocket- . HTTP- , WebSocket- , .

, onConnect.

wsServer.on('connection', onConnect);
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

onConnection ws-, .

onConnect , wsClient. wsClient: message close.

message - .

close - .

onConnect, .

onConnect:

function onConnect(wsClient) {
  console.log(' ');
  //    
  wsClient.send('');
wsClient.on('message', function(message) {
    /*     */
  }
wsClient.on('close', function() {
    //    
    console.log(' ');
  }
}
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

close .

. , JSON-. JSON , .

JSON :

{
  action: 'ECHO' | 'PING',
  data?: string //  
}
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

, :

• echo-, data

  
  
  
  
  

• ping, pong

  
  
  
  
  

• , " "

  
  
  
  
  

:

try {
  //   ,    JSON-
  const jsonMessage = JSON.parse(message);
  switch (jsonMessage) {
    case 'ECHO':
      wsClient.send(jsonMessage.data);
      break;
    case: 'PING':
      setTimeout(function() {
        wsClient.send('PONG');
      }, 2000);
      break;
    default:
      console.log(' ');
      break;
  }
} catch (error) {
  console.log('', error);
}
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

, PING , 2 .

server.js , , .

console.log('   9000 ');
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

:

node server.js
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

ws://localhost:9000. :

• Windows Linux (Ctrl + C)

  
  
  
  
  

• MacOs (Cmd + C)

  
  
  
  
  

,

Window:

ipconfig
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

Linux MacOS:

ifconfig
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

192.168.0.15, ws://192.168.0.15:9000.

, F12. DevTools, :

const myWs = new WebSocket('ws://localhost:9000');
//       
myWs.onopen = function () {
  console.log('');
};
//    
myWs.onmessage = function (message) {
  console.log('Message: %s', message.data);
};
//    echo-  
function wsSendEcho(value) {
  myWs.send(JSON.stringify({action: 'ECHO', data: value.toString()}));
}
//     ping  
function wsSendPing() {
  myWs.send(JSON.stringify({action: 'PING'}));
}
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

. wsSendPing:

wsSendPing()
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

2 , :

Message: PONG

Call the wsSendEcho function, for example, with the content "Test!", And the console will output:

Message: Test!

That's all! Who liked it, put Like, subscribe. Good to all!

Link to full GitHub code