error-cause-polyfill
Version:
Polyfill `error.cause`
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Markdown
[](https://www.npmjs.com/package/error-cause-polyfill)
[](https://unpkg.com/error-cause-polyfill?module)
[](/src/main.d.ts)
[](https://codecov.io/gh/ehmicky/error-cause-polyfill)
[](https://bundlephobia.com/package/error-cause-polyfill)
[](https://fosstodon.org/@ehmicky)
[](https://medium.com/@ehmicky)
Polyfill `error.cause`.
[`error.cause`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Error/cause)
is a recent JavaScript feature to wrap errors.
```js
try {
doSomething()
} catch (cause) {
throw new Error('message', { cause })
}
```
Unfortunately, it is
[not supported](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Error/cause#browser_compatibility)
in Node <16.9.0, Opera nor Safari <15. This library adds support for it in those
environments.
# Differences with other polyfills
Unlike [`error-cause`](https://github.com/es-shims/error-cause):
- The package size is small (~50kB vs ~2000kB)
- `Error` child classes still work
- [`Error.stackTraceLimit`](https://nodejs.org/api/errors.html#errorstacktracelimit)
still works
- `error.stack` does not include the polyfill's internal code (in Node.js and
Chrome)
Unlike
[`core-js`](https://github.com/zloirock/core-js)/[Babel](https://github.com/babel/babel),
this does not require adding `core-js` as a production dependency (~1000kB).
# Install
```bash
npm install error-cause-polyfill
```
This package works in both Node.js >=18.18.0 and
[browsers](https://raw.githubusercontent.com/ehmicky/dev-tasks/main/src/browserslist).
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
## polyfill()
_Return value_: `() => void`
Modifies the global error classes (`Error`, `TypeError`, etc.) so they support
`error.cause`. If `error.cause` is already supported, this is a noop.
<!-- eslint-disable import/no-unassigned-import, import/extensions, n/file-extension-in-import -->
```js
import 'error-cause-polyfill/auto'
try {
doSomething()
} catch (cause) {
throw new Error('message', { cause })
}
```
Or alternatively:
```js
import { polyfill } from 'error-cause-polyfill'
polyfill()
try {
doSomething()
} catch (cause) {
throw new Error('message', { cause })
}
```
This returns a function to undo everything.
```js
import { polyfill } from 'error-cause-polyfill'
const undoPolyfill = polyfill()
undoPolyfill()
```
## getErrors()
_Return value_: `object`
Returns an object with each error class (`Error`, `TypeError`, etc.) but with
`error.cause` support. If `error.cause` is already supported, this returns the
global error classes as is.
Unlike [`polyfill()`](#polyfill), this does not modify the global error classes.
<!-- eslint-disable no-shadow -->
```js
import { getErrors } from 'error-cause-polyfill'
const Errors = getErrors()
try {
doSomething()
} catch (cause) {
throw new Errors.Error('message', { cause })
}
```
## hasSupport()
_Return value_: `boolean`
Returns whether the global error classes currently support `error.cause`.
```js
import { hasSupport, polyfill } from 'error-cause-polyfill'
console.log(hasSupport()) // false
polyfill()
console.log(hasSupport()) // true
```
# Related projects
- [`modern-errors`](https://github.com/ehmicky/modern-errors): Handle errors in
a simple, stable, consistent way
- [`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
- [`handle-cli-error`](https://github.com/ehmicky/handle-cli-error): 💣 Error
handler for CLI applications 💥
- [`log-process-errors`](https://github.com/ehmicky/log-process-errors): Show
some ❤ to Node.js process errors
- [`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!
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