Server Error Event

Stage 2: the HTTP server 'error' event. It fires on a server-level failure — in practice a bind failure such as EADDRINUSE (the port is already in use) or EACCES (a privileged port without permission). Without a listener the failure surfaces as an uncaught, process-aborting error (Node parity); with one, the listener receives the Error and the process keeps running.

Here one server binds a port successfully, then a second server tries to bind the same port and its 'error' listener catches the EADDRINUSE. The listener runs synchronously at listen time.

import http from 'http';

const first = http.createServer((req: http.IncomingMessage, res: http.ServerResponse) => {
  res.end("first");
});
first.listen(8422);

const second = http.createServer((req: http.IncomingMessage, res: http.ServerResponse) => {
  res.end("second");
});

second.on('error', (err: NodeJS.ErrnoException) => {
  console.log("server error:", err.code);
  console.log("message:", err.message);
  process.exit(0);
});

second.listen(8422);
console.log("unreachable — the bind failure fired the error listener");

View source on GitHubexamples/http/server_error_event.ts

← Server Connection Event Client Session →