How to use ws to develop nodejs

With the continuous development of Node.js, Websockets have become a popular way to achieve real-time two-way communication in Node.js. This article will introduce how to use the ws module to build applications with real-time communication capabilities in Node.js.

1. What are Websockets?

Websockets is a technology that supports real-time two-way communication. Compared with the HTTP protocol, which can only perform one-way requests, Websockets can establish a two-way communication channel, which allows the client and server to transmit data in real time without the need for the client to continuously initiate requests to the server, saving HTTP The protocol generates a large amount of network bandwidth due to polling.

2. Introduction to ws module

The ws module is a module in Node.js used to implement Websockets, and it is also a popular implementation method. Its API is extremely simple and does not have any external dependencies, making it easy to use. The following will introduce how to use the ws module to implement a simple chat room.

3. Initialize a new Node.js project

First, install the latest version of Node.js on your system. After the installation is complete, open your terminal and go to the directory where you want to create the project, enter the following command:

mkdir ws_demo && cd ws_demo && npm init

Then follow the prompts step by step to configure your project.

4. Install and reference the ws module

Use the following command in the project directory to install the ws module:

npm install ws

Now introduce the ws module into your server.js file:

const WebSocket = require('ws');

5. Create a websockets server

In order to create a websockets server, you need to listen for incoming connection requests on a certain port of the server. In Node.js, use the following code to create a Websocket server:

const wss = new WebSocket.Server({ port: 8080 });

wss.on('connection', (ws) => {
  console.log('Client connected');
});

This code will create a Websocket server on port 8080. When a new client successfully connects to the server, the server prints a "Client connected" message.

6. Server-side broadcast message

Now, we have created a WebSocket server and can receive client connections. But it has little practical effect. Let's try adding some real functionality to it. We can let the server broadcast some messages, which will be received by all clients connected to the server.

Add the following code within the wss.on() method:

wss.on('connection', (ws) => {
  console.log('Client connected');
  ws.on('message', (message) => {
    console.log(`Received message => ${message}`)
    wss.clients.forEach((client) => {
      if (client.readyState === WebSocket.OPEN) {
        client.send(`Broadcast message => ${message}`);
      }
    });
  });
});

This code adds an event listener when the client connection is successful. When a new message arrives, the server records it in the log and loops through all currently connected clients using wss.clients.forEach(), broadcasting the message to all clients when available.

7. Test

Now, all the steps of installing the ws module and developing the server-side code have been completed. You only need to use the client to test it. Using a Websocket client, there are many different browser extensions and command line tools available. Use your favorite tool to connect to wss://localhost:8080. You will see a successful connection message and your browser extension will display the message on top of the message broadcast from the server.

Summary

In this article, we have introduced how to use the ws module to develop Websockets services based on Node.js.

As Websockets continues to develop and expand, it is becoming more and more important in web development, especially in real-time communication, such as chat applications, online games, etc. Now, with just a few lines of code, you can implement a simple chat room in Node.js.

Although this article only introduces part of the functions of the ws module, I believe that students can learn from it the knowledge points of developing real-time communication based on Node.js, and master certain skills and experience, which can be used for future work and Provide reference for learning.

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