  
  log-process-errors logo

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[📰 Medium article.](https://medium.com/@ehmicky/node-js-process-errors-are-broken-193980f0a77b)

Show some ❤️ to Node.js process errors.

This improves process errors:
[uncaught](https://nodejs.org/api/process.html#process_event_uncaughtexception)
exceptions,
[unhandled](https://nodejs.org/api/process.html#process_event_unhandledrejection)
promises, promises
[handled too late](https://nodejs.org/api/process.html#process_event_rejectionhandled)
and [warnings](https://nodejs.org/api/process.html#process_event_warning).

# Features

- Stack traces for warnings and
  [`rejectionHandled`](https://nodejs.org/api/process.html#process_event_rejectionhandled)
- [Single event handler](#onerror) for all process errors
- Ignore [duplicate](#onerror) process errors
- [Normalize](#error) invalid errors
- [Process exit](#exit) is graceful and can be prevented

# Install

Production code (e.g. a server) can install this either as a production or
development dependency:

```bash
npm install log-process-errors
```

However, libraries should install this as a development dependency:

```bash
npm install -D log-process-errors
```

This is because logging is modified globally and libraries users might not
expect this side-effect. Also, this might lead to conflicts between libraries.

This package works in Node.js >=18.18.0.

This is an ES module. It must be loaded using
[an `import` or `import()` statement](https://gist.github.com/sindresorhus/a39789f98801d908bbc7ff3ecc99d99c),
not `require()`. If TypeScript is used, it must be configured to
[output ES modules](https://www.typescriptlang.org/docs/handbook/esm-node.html),
not CommonJS.

# API

## logProcessErrors(options?)

[`options`](#options) `object?`\
_Return value_: `() => void`

Start handling process errors.

```js
import logProcessErrors from 'log-process-errors'
logProcessErrors(options)
```

The return value restores Node.js default behavior.

```js
const restore = logProcessErrors(options)
restore()
```

## Options

### exit

_Type_: `boolean`

Whether to exit the process on
[uncaught exceptions](https://nodejs.org/api/process.html#process_event_uncaughtexception)
or
[unhandled promises](https://nodejs.org/api/process.html#process_event_unhandledrejection).

This is `false` by default if other libraries are listening to those events, so
they can perform the exit instead. Otherwise, this is `true`.

If some tasks are still ongoing, the exit waits for them to complete up to 3
seconds.

### onError

_Type_: `(error, event) => Promise<void> | void`\
_Default_: `console.error(error)`

Function called once per process error. Duplicate process errors are ignored.

```js
// Log process errors with Winston instead
logProcessErrors({
  onError: (error, event) => {
    winstonLogger.error(error.stack)
  },
})
```

#### error

_Type_: `Error`

The process error. This is guaranteed to be a
[normalized](https://github.com/ehmicky/normalize-exception) error instance. A
short description of the [event](#event) is also appended to its message.

#### event

_Type_: `Event`

Process event name among:
[`'uncaughtException'`](https://nodejs.org/api/process.html#process_event_uncaughtexception),
[`'unhandledRejection'`](https://nodejs.org/api/process.html#process_event_unhandledrejection),
[`'rejectionHandled'`](https://nodejs.org/api/process.html#process_event_rejectionhandled),
[`'warning'`](https://nodejs.org/api/process.html#process_event_warning).

# Related projects

- [`modern-errors`](https://github.com/ehmicky/modern-errors): Handle errors in
  a simple, stable, consistent way
- [`modern-errors-process`](https://github.com/ehmicky/modern-errors-process):
  Handle process errors
- [`error-custom-class`](https://github.com/ehmicky/error-custom-class): Create
  one error class
- [`error-class-utils`](https://github.com/ehmicky/error-class-utils): Utilities
  to properly create error classes
- [`error-serializer`](https://github.com/ehmicky/error-serializer): Convert
  errors to/from plain objects
- [`normalize-exception`](https://github.com/ehmicky/normalize-exception):
  Normalize exceptions/errors
- [`is-error-instance`](https://github.com/ehmicky/is-error-instance): Check if
  a value is an `Error` instance
- [`merge-error-cause`](https://github.com/ehmicky/merge-error-cause): Merge an
  error with its `cause`
- [`set-error-class`](https://github.com/ehmicky/set-error-class): Properly
  update an error's class
- [`set-error-message`](https://github.com/ehmicky/set-error-message): Properly
  update an error's message
- [`wrap-error-message`](https://github.com/ehmicky/wrap-error-message):
  Properly wrap an error's message
- [`set-error-props`](https://github.com/ehmicky/set-error-props): Properly
  update an error's properties
- [`set-error-stack`](https://github.com/ehmicky/set-error-stack): Properly
  update an error's stack
- [`error-cause-polyfill`](https://github.com/ehmicky/error-cause-polyfill):
  Polyfill `error.cause`
- [`handle-cli-error`](https://github.com/ehmicky/handle-cli-error): 💣 Error
  handler for CLI applications 💥
- [`error-http-response`](https://github.com/ehmicky/error-http-response):
  Create HTTP error responses
- [`winston-error-format`](https://github.com/ehmicky/winston-error-format): Log
  errors with Winston

# Support

For any question, _don't hesitate_ to [submit an issue on GitHub](../../issues).

Everyone is welcome regardless of personal background. We enforce a
[Code of conduct](CODE_OF_CONDUCT.md) in order to promote a positive and
inclusive environment.

# Contributing

This project was made with ❤️. The simplest way to give back is by starring and
sharing it online.

If the documentation is unclear or has a typo, please click on the page's `Edit`
button (pencil icon) and suggest a correction.

If you would like to help us fix a bug or add a new feature, please check our
[guidelines](CONTRIBUTING.md). Pull requests are welcome!

Thanks go to our wonderful contributors:

ehmicky (https://fosstodon.org/@ehmicky)
💻 (https://github.com/ehmicky/log-process-errors/commits?author=ehmicky) 🎨 🤔 📖 (https://github.com/ehmicky/log-process-errors/commits?author=ehmicky)
     
Steven Vachon (https://svachon.com)
💬
     
Hongarc (https://github.com/Hongarc)
📖 (https://github.com/ehmicky/log-process-errors/commits?author=Hongarc) 💻 (https://github.com/ehmicky/log-process-errors/commits?author=Hongarc)
     
Andy Brenneke (https://github.com/abrenneke)
🐛 (https://github.com/ehmicky/log-process-errors/issues?q=author%3Aabrenneke)

