Doing a cleanup action just before Node.js exits

Question

I want to tell Node.js to always do something just before it exits, for whatever reason — Ctrl+C, an exception, or any other reason.

I tried th

Answer 1

After playing around with other answer, here is my solution for this task. Implementing this way helps me centralize cleanup in one place, preventing double handling the cleanup.

1. I would like to route all other exiting codes to 'exit' code.

const others = [`SIGINT`, `SIGUSR1`, `SIGUSR2`, `uncaughtException`, `SIGTERM`]
others.forEach((eventType) => {
    process.on(eventType, exitRouter.bind(null, { exit: true }));
})

2. What the exitRouter does is calling process.exit()

function exitRouter(options, exitCode) {
   if (exitCode || exitCode === 0) console.log(`ExitCode ${exitCode}`);
   if (options.exit) process.exit();
}

3. On 'exit', handle the clean up with a new function

function exitHandler(exitCode) {
  console.log(`ExitCode ${exitCode}`);
  console.log('Exiting finally...')
}

process.on('exit', exitHandler)

For the demo purpose, this is link to my gist. In the file, i add a setTimeout to fake the process running.

If you run node node-exit-demo.js and do nothing, then after 2 seconds, you see the log:

The service is finish after a while.
ExitCode 0
Exiting finally...

Else if before the service finish, you terminate by ctrl+C, you'll see:

^CExitCode SIGINT
ExitCode 0
Exiting finally...

What happened is the Node process exited initially with code SIGINT, then it routes to process.exit() and finally exited with exit code 0.