README.md

Polyfill error.cause.

error.cause is a recent JavaScript feature to wrap errors.

try {
  doSomething()
} catch (cause) {
  throw new Error('message', { cause })
}

Unfortunately, it is not supported in Node <16.9.0, Opera nor Safari <15. This library adds support for it in those environments.

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Differences with other polyfills

Unlike error-cause:

• The package size is small (~50kB vs ~2000kB)
• Error child classes still work
• Error.stackTraceLimit still works
• error.stack does not include the polyfill's internal code (in Node.js and Chrome)

Unlike core-js/Babel, this does not require adding core-js as a production dependency (~1000kB).

Install

npm install error-cause-polyfill

This package works in both Node.js >=18.18.0 and browsers.

This is an ES module. It must be loaded using an import or import() statement, not require(). If TypeScript is used, it must be configured to output ES modules, 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.

import 'error-cause-polyfill/auto'

try {
  doSomething()
} catch (cause) {
  throw new Error('message', { cause })
}

Or alternatively:

import { polyfill } from 'error-cause-polyfill'

polyfill()

try {
  doSomething()
} catch (cause) {
  throw new Error('message', { cause })
}

This returns a function to undo everything.

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(), this does not modify the global error classes.

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.

import { hasSupport, polyfill } from 'error-cause-polyfill'

console.log(hasSupport()) // false
polyfill()
console.log(hasSupport()) // true

Related projects

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

Support

For any question, don't hesitate to submit an issue on GitHub.

Everyone is welcome regardless of personal background. We enforce a Code of conduct in order to promote a positive and inclusive environment.

Contributing

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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. Pull requests are welcome!