Broadcasting to connected clients in Node.js - Mini Project: Build & Apply

Broadcasting to connected clients

📖 Scenario: You are building a simple chat server using Node.js. Multiple clients can connect to the server, and when one client sends a message, the server should send that message to all connected clients.

🎯 Goal: Create a Node.js server that keeps track of connected clients and broadcasts messages to all of them.

📋 What You'll Learn

Create an array to store connected clients

Add a new client to the array when they connect

Write a function to send a message to all clients in the array

Call the broadcast function when a client sends a message

💡 Why This Matters

🌍 Real World

Chat servers, multiplayer games, and live notifications use broadcasting to keep all users updated in real time.

💼 Career

Understanding how to manage multiple clients and broadcast messages is essential for backend developers working on real-time applications.

1

Create an array to store connected clients

Create an empty array called clients to hold all connected client objects.

Node.js

// Create an empty array called clients
// Your code here

Need a hint?

Use [] to create an empty array and assign it to clients.

2

Add new clients to the array when they connect

Write a function called addClient that takes a client parameter and adds it to the clients array using clients.push(client).

Node.js

const clients = []

// Write function addClient(client) to add client to clients array
// Your code here

Need a hint?

Define a function named addClient that uses push to add the client to the array.

3

Write a function to broadcast messages to all clients

Create a function called broadcast that takes a message parameter. Use a for loop with const client of clients to send the message to each client by calling client.send(message).

Node.js

const clients = [];

function addClient(client) {
    clients.push(client);
}

// Write function broadcast(message) to send message to all clients
// Your code here

Need a hint?

Loop over clients and call send on each client with the message.

4

Call broadcast when a client sends a message

Inside a function called onMessage that takes client and message parameters, call broadcast(message) to send the message to all clients.

Node.js

const clients = [];

function addClient(client) {
    clients.push(client);
}

function broadcast(message) {
    for (const client of clients) {
        client.send(message);
    }
}

// Write function onMessage(client, message) that calls broadcast(message)
// Your code here

Need a hint?

Define onMessage to call broadcast with the message.