Socket.io

Question 1

What is socket.io

Answer 1

Socket.IO enables real-time, bidirectional and event-based communication. It creates a persistent connection between client and server

Question 2

full-duplex communication

Answer 2

Bi-diretional communitcation where the server can initiate communication with the client and vica versa.

Question 3

Which npm library allows us to work with socket.io

Answer 3

npm i socket.io

Question 4

How to add socket.io to the a client?

Answer 4

In the html file add the following scripts to the body:

then in the public directory create a chat.js file with the following:

io();

Question 5

How to setup the server to work with sockets?

Answer 5

1. setup an express server

const app = express();

2. Manually create an http server outside of express

const server = http.createServer(app);

3. Pass the raw http server into socket.io

const io = socketio(server);

Question 6

Difference between io.emit, socket.broadcast.emit and socket.emit?

Answer 6

socket.emit emits an event to a single connection, while io emits an event to every single connection. broadcast.emit sends a message to all connections except for the one that triggers it.