sse-client.js

const SSE = new EventSource('http://localhost:3000');
SSE.onmessage = (event) => {
  const obj = JSON.parse(event.data);
  console.log(obj);
};

sse-server.js

const http = require('http');

const server = http.Server((req, res) => {
  const ip = req.headers['x-forwarded-for'] || req.connection.remoteAddress;
  const id = Math.random().toString(36).substr(2, 5);

  console.log(`[START][${id}]`, req.method, req.url, ip);

  const sseHeaders = {
    Connection: 'keep-alive',
    'Access-Control-Allow-Origin': '*',
    'Cache-Control': 'no-cache',
    'Content-Type': 'text/event-stream',
  };

  res.writeHead(200, sseHeaders);
  res.write('');

  const interval = setInterval(() => {
    const data = {
      id,
      username: 'FelipeGrijo',
      date: new Date(),
    };

    res.write(`data:${JSON.stringify(data)}\n\n`);
  }, 3000);

  req.on('close', () => {
    clearInterval(interval);
    console.log(`[CLOSE][${id}]`, req.method, req.url, ip);
  });
});

server.listen(3000, '0.0.0.0', () => {
  console.log(`Server started on ${server.address().address}:${server.address().port}`);
});