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How do you handle uncaught exceptions and unhandled promise rejections in Node.js?

Q: How do you handle uncaught exceptions and unhandled promise rejections in Node.js?

**TL;DR.** Listen on process.on('uncaughtException', …) and process.on('unhandledRejection', …) as **last-resort** handlers: **log**, then **gracefully shut down and let a supervisor restart** — because after an uncaught error the process is in an **undefined state**. Don't use them to "keep running" as if nothing happened. uncaughtException / unhandledRejection log error + cleanup</te

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Detail the global event listeners used to catch unexpected application-level errors and prevent silent failures.

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Last-resort handlers

process.on('unhandledRejection', (reason) => {
  log.error({ reason }, 'unhandledRejection');
  throw reason;                       // promote to uncaughtException
});

process.on('uncaughtException', (err) => {
  log.fatal(err, 'uncaughtException — restarting');
  server.close(() => process.exit(1)); // drain, then let supervisor restart
  setTimeout(() => process.exit(1), 5000).unref();
});

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