# is-error-instance > Check if a value is an `Error` instance Latest version **3.0.1** (published 2025-03-29) · MIT license · 0 weekly downloads ## Install ```sh npm install is-error-instance pnpm add is-error-instance yarn add is-error-instance bun add is-error-instance ``` ## Health **Score 55/100 (C)** — status: stable. Positive: has types; esm support; no vulnerabilities; high maintenance score; high quality score. Warnings: low downloads. Negative: stale. ## Facts | | | |---|---| | Version | 3.0.1 | | Published | 2025-03-29 | | First published | 2022-10-13 | | Weekly downloads | 0 | | License | MIT | | TypeScript types | bundled | | Module format | ESM + CommonJS | | Node | >=18.18.0 | | Dependencies | 0 | | Unpacked size | 9.2 KB | | Known vulnerabilities | 0 | | Install scripts | no | | GitHub stars | 4 | | Author | ehmicky | | Maintainers | ehmicky | | Keywords | browser, cross-realm, dom, error, error-handle, error-handler, error-handlers, error-handling, error-monitoring, error-reporting, errors, exception, exception-handling, instanceof, javascript, library, monitoring, nodejs, testing, typescript | ## Links - npm: https://www.npmjs.com/package/is-error-instance - Repository: https://github.com/ehmicky/is-error-instance - Homepage: https://www.github.com/ehmicky/is-error-instance - Issues: https://github.com/ehmicky/is-error-instance/issues - npm.io page: https://npm.io/package/is-error-instance ## Alternatives - [@sentry/react-native](https://npm.io/package/@sentry/react-native.md) — 2.6M weekly downloads - [@ardatan/aggregate-error](https://npm.io/package/@ardatan/aggregate-error.md) — 708.1K weekly downloads - [custom-error-generator](https://npm.io/package/custom-error-generator.md) — 2.0K weekly downloads - [@technik-sde/prosemirror-recreate-transform](https://npm.io/package/@technik-sde/prosemirror-recreate-transform.md) — 1.5K weekly downloads - [@suchipi/error-utils](https://npm.io/package/@suchipi/error-utils.md) — 78 weekly downloads ## Recent versions - 3.0.1 (latest) — 2025-03-29 - 3.0.0 — 2023-10-28 - 2.0.0 — 2023-05-13 - 1.6.0 — 2022-12-17 - 1.5.0 — 2022-12-12 - 1.4.0 — 2022-12-10 - 1.3.0 — 2022-11-11 - 1.2.0 — 2022-11-07 - 1.1.0 — 2022-10-13 - 1.0.0 — 2022-10-13 - 0.0.1 — 2022-10-13 ## README [![Node](https://img.shields.io/badge/-Node.js-808080?logo=node.js&colorA=404040&logoColor=66cc33)](https://www.npmjs.com/package/is-error-instance) [![Browsers](https://img.shields.io/badge/-Browsers-808080?logo=firefox&colorA=404040)](https://unpkg.com/is-error-instance?module) [![TypeScript](https://img.shields.io/badge/-Typed-808080?logo=typescript&colorA=404040&logoColor=0096ff)](/src/main.ts) [![Codecov](https://img.shields.io/badge/-Tested%20100%25-808080?logo=codecov&colorA=404040)](https://codecov.io/gh/ehmicky/is-error-instance) [![Minified size](https://img.shields.io/bundlephobia/minzip/is-error-instance?label&colorA=404040&colorB=808080&logo=webpack)](https://bundlephobia.com/package/is-error-instance) [![Mastodon](https://img.shields.io/badge/-Mastodon-808080.svg?logo=mastodon&colorA=404040&logoColor=9590F9)](https://fosstodon.org/@ehmicky) [![Medium](https://img.shields.io/badge/-Medium-808080.svg?logo=medium&colorA=404040)](https://medium.com/@ehmicky) Check if a value is an `Error` instance. This is like `value instanceof Error` except it works across realms, such as iframes or Node.js [`vm`](https://nodejs.org/api/vm.html). # Example ```js import isErrorInstance from 'is-error-instance' isErrorInstance(new Error('')) // true isErrorInstance('') // false const CrossRealmError = vm.runInNewContext('Error') isErrorInstance(new CrossRealmError('')) // true isErrorInstance(new TypeError('')) // true isErrorInstance(new AnyOtherError('')) // true isErrorInstance(new DOMException('')) // true isErrorInstance(new DOMError('')) // true isErrorInstance(new Proxy(new Error(''), {})) // true isErrorInstance( new Proxy(new Error(''), { getPrototypeOf: () => { throw new Error('') }, }), ) // false ``` # Install ```bash npm install is-error-instance ``` 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 ## isErrorInstance(value) `value` `any`\ _Return value_: `boolean` # 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 - [`merge-error-cause`](https://github.com/ehmicky/merge-error-cause): Merge an error with its `cause` - [`normalize-exception`](https://github.com/ehmicky/normalize-exception): Normalize exceptions/errors - [`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 💥 - [`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! --- _Source: https://npm.io/package/is-error-instance · Machine-readable twin of the npm.io package page. Health data is recomputed on every publish._