text: const http= require('http');
  const server = http.createServer();
  
  server.on('request', (req,res) => {
      if(req.method === 'POST' && req.url == "/echo" ){
          let body = [];
          req.on('data',chunk => {
              body.push(chunk);
          })
          .on('end', () => {
              res.writeHeader(200,{'Content-Type': 'text/plain'});
              body = Buffer.concat(body).toString();
              res.end(body);
          })
      }else{
          res.statusCode=404;
          res.end('Error 404');
      }
      
  });
  
  server.listen(3000);
  console.log('Servidor en la url http://localhost:3000');