This is the emit Event written on the client-side.

socket.emit('test', 'This is a message', () => {
console.log('Callback Function');
});

This is the broadcaster written on the server-side.

io.on('connection', (socket) => {
socket.on('test', (message, callback) => {
console.log(message);
callback();
})}

Whenever a 'test' event emits from client-side it gets executed on server-side. console.log(message) prints the message 'This is a message' on client-side (basically in express server logs), which is correct. But how does the callback function prints the message 'Callback Function' on browser console, while the callback was called on the server-side?