how to run a local server mac socket.io code example

Example 1: js socket.emit

const socket = io('ws://localhost:3000');
socket.on('connect', () => {  
  // either with send()  
  socket.send('Hello!');
  // or with emit() and custom event names  
  socket.emit('salutations', 'Hello!', { 'mr': 'john' }, Uint8Array.from([1, 2, 3, 4]));});
// handle the event sent with socket.send()
socket.on('message', data => {
  console.log(data);
});
// handle the event sent with socket.emit()
socket.on('greetings', (elem1, elem2, elem3) => {
  console.log(elem1, elem2, elem3);
});

Example 2: socket.io client send data node js server

var socket = io.connect('http://localhost');
socket.emit('my other event', { my: 'data' });
//server side
io.sockets.on('connection', function (socket) {
  socket.on('my other event', function (data) {
    console.log(data);
  });
});
//sending data from the user via a socket.io
socket.on("test", function (data) {
    data.forEach(obj => {
        console.log("Yer : " + obj.yer + ", Lat : " + obj.lat + ", Long : " + obj.lng);
    })
});