`process.on()`

Registers a listener for process-level events and signals.

Since Node 0.x Spec ↗

Syntax

process.on(event, listener)

Parameters

Name	Type	Required	Description
`event`	`string`	Yes	The event name, e.g. `'exit'`, `'SIGINT'`, `'SIGTERM'`, `'uncaughtException'`, `'unhandledRejection'`, `'beforeExit'`.
`listener`	`function`	Yes	The handler invoked when the event fires.

Returns

process — The process object, for chaining.

Examples

process.on('SIGINT', () => {
  console.log('shutting down');
  process.exit(0);
});

Output

shutting down

process.on('unhandledRejection', (reason) => {
  console.error('unhandled rejection:', reason);
  process.exitCode = 1;
});

Output

unhandled rejection: Error: boom

Notes

Use `SIGINT`/`SIGTERM` for graceful shutdown (close servers and DB pools). Inside `'exit'` only synchronous work runs. Treat `'uncaughtException'` as a last resort for logging then exiting, not for resuming normal operation.