code: function normalizePort (val) {
          let port = parseInt(val, 10);
  
          if (isNaN(port)) {
            // named pipe
            return val;
          }
  
          if (port >= 0) {
            // port number
            return port;
          }
  
          return false;
        }
docs: Normalize a port into a number, string, or false.