https://github.com/fastify/fastify-error
A small utility, used by Fastify itself, for generating consistent error objects across your codebase and plugins
https://github.com/fastify/fastify-error
fastify fastify-library
Last synced: about 1 month ago
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A small utility, used by Fastify itself, for generating consistent error objects across your codebase and plugins
- Host: GitHub
- URL: https://github.com/fastify/fastify-error
- Owner: fastify
- License: mit
- Created: 2020-06-21T13:38:33.000Z (about 5 years ago)
- Default Branch: main
- Last Pushed: 2025-05-01T16:22:25.000Z (about 2 months ago)
- Last Synced: 2025-05-07T04:05:58.455Z (about 2 months ago)
- Topics: fastify, fastify-library
- Language: JavaScript
- Homepage: https://npmjs.com/package/@fastify/error
- Size: 120 KB
- Stars: 120
- Watchers: 16
- Forks: 19
- Open Issues: 5
-
Metadata Files:
- Readme: README.md
- License: LICENSE
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README
# @fastify/error
[](https://github.com/fastify/fastify-error/actions/workflows/ci.yml)
[](https://www.npmjs.com/package/@fastify/error)
[](https://github.com/neostandard/neostandard)
A small utility, used by Fastify itself, for generating consistent error objects across your codebase and plugins.
### Install
```
npm i @fastify/error
```
### Usage
The module exports a function that you can use for consistent error objects, it takes 4 parameters:
```
createError(code, message [, statusCode [, Base]])
```
- `code` (`string`, required) - The error code, you can access it later with `error.code`. For consistency, we recommend prefixing plugin error codes with `FST_`
- `message` (`string`, required) - The error message. You can also use interpolated strings for formatting the message.
- `statusCode` (`number`, optional) - The status code that Fastify will use if the error is sent via HTTP.
- `Base` (`ErrorConstructor`, optional) - The base error object that will be used. (eg `TypeError`, `RangeError`)
```js
const createError = require('@fastify/error')
const CustomError = createError('ERROR_CODE', 'Hello')
console.log(new CustomError()) // error.message => 'Hello'
```
How to use an interpolated string:
```js
const createError = require('@fastify/error')
const CustomError = createError('ERROR_CODE', 'Hello %s')
console.log(new CustomError('world')) // error.message => 'Hello world'
```
How to add cause:
```js
const createError = require('@fastify/error')
const CustomError = createError('ERROR_CODE', 'Hello %s')
console.log(new CustomError('world', {cause: new Error('cause')}))
// error.message => 'Hello world'
// error.cause => Error('cause')
```
### TypeScript
It is possible to limit your error constructor with a generic type using TypeScript:
```ts
const CustomError = createError<[string]>('ERROR_CODE', 'Hello %s')
new CustomError('world')
//@ts-expect-error
new CustomError(1)
```
## License
Licensed under [MIT](./LICENSE).