How to send and receive data in Socket IO?

Socket.io is a library to abstract the WebSocket connections. According to the official website of socket io, Socket.IO is a library that enables low-latency, bidirectional and event-based communication between a client and a server.

What does it mean by event-based? We can send and receive data in Socket by using the following code block. We can send an event from the server and receive it in the client and vice-versa.

To Receive Data
socket.on("message", (hello) => {
console.log(hello); // world
});

To send Data
socket.emit("message", "hello");

In general, the code for sending and receiving data is
Receiving Data: socket.on(eventName, listenerFn)
Sending Data : socket.emit(eventName, Data)

We have to use same eventName for sending and catching data. There are some pre-defined events in Socket Io but we can also make our own custom events provided that the same event name is to be used in both client and server.