socket in node

client.js

const net = require('net');

socket = net.createConnection(54321);
socket.on('data', (data) => {
  console.log(data.toString().trim());
});
socket.on('end', () => {
  console.log('socket end');
  socket.end();
});
//socket.setKeepAlive(true);
socket.write('hello~');
setTimeout(() => {
  if (!socket.destroyed)
    socket.write('hello again XD\n');
  else
    console.log('qq');
}, 3000);

server.js

const net = require('net');

server = net.createServer((socket) => {
  socket.setTimeout(2000, () => {
    socket.end();
  });
  socket.on('data', (data) => {
    console.log(data.toString().trim());
    socket.write('hi client');
  });
  socket.on('end', () => {
    console.log('client bye');
  });
});

server.listen(54321, () => {
  console.log(`listening at localhost:54321`);
});