Properly create error classes.

Useful utilities when creating custom error classes.

• Ponyfill error.cause on older Node.js and browsers
• Properly set error.name
• Fix issues when Error has been polyfilled

import { ensureCorrectClass, ponyfillCause, setErrorName, } from 'error-class-utils' export class CustomError extends Error { constructor(message, parameters) { super(message, parameters) // Fix some issues when `Error` has been polyfilled ensureCorrectClass(this, new.target) // Ponyfill `error.cause` on old Node.js/browsers ponyfillCause(this, parameters) } } // Properly set `error.name` as a non-enumerable and inherited property setErrorName(CustomError, 'CustomError')

import { CustomError } from './errors.js' const cause = new Error('innerMessage') const error = new CustomError('message', { cause }) console.log(error instanceof CustomError) // true console.log(error.name) // 'CustomError' console.log(error.cause) // Error: innerMessage ...

npm install error-class-utils

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.

error Error
new.target typeof Error
Return value: void

Some Error polyfills (such as es-shims/error-cause) prevent extending from it. This fixes it.

The second argument must be new.target. This must be called directly inside a class constructor, after super(message, parameters).

import { ensureCorrectClass } from 'error-class-utils' class CustomError extends Error { constructor(message, parameters) { super(message, parameters) ensureCorrectClass(this, new.target) } } // Thanks to `ensureCorrectClass()`, this is now always true even when // `Error` has been polyfilled console.log(new CustomError('message') instanceof CustomError) // true

error Error
parameters ErrorParams?
Return value: void

Ponyfills error.cause on older Node.js and browsers.

This must be called inside a class constructor, after super(message, parameters).

import { ponyfillCause } from 'error-class-utils' class CustomError extends Error { constructor(message, parameters) { super(message, parameters) ponyfillCause(this, parameters) } } try { throw new Error('innerMessage') } catch (cause) { // Works on any platforms thanks to ponyfill const error = new CustomError('message', { cause }) console.log(error.cause.message) // 'innerMessage' }

ErrorClass typeof Error
name string
Return value: void

Set an ErrorClass's name.

This must be performed on an error class, not instance. Unlike setting this.name = '...' inside an error's constructor, this follows the native Error classes' pattern where error.name:

• Ends with the Error suffix
• Matches the constructor's name
• Is inherited
• Is non-enumerable

import { setErrorName } from 'error-class-utils' class CustomError extends Error {} setErrorName(CustomError, 'CustomError') console.log(CustomError.name) // 'CustomError' console.log(CustomError.prototype.name) // 'CustomError' const error = new CustomError('message') console.log(error.name) // 'CustomError' console.log(Object.keys(error).includes('name')) // false

• modern-errors: Handle errors in a simple, stable, consistent way
• error-custom-class: Create one error class
• 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
• error-cause-polyfill: Polyfill error.cause
• handle-cli-error: 💣 Error handler for CLI applications 💥
• beautiful-error: Prettify error messages and stacks
• log-process-errors: Show some ❤ to Node.js process errors
• error-http-response: Create HTTP error responses
• winston-error-format: Log errors with Winston

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

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