fault

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Functional errors with formatted output.

Contents

* What is this?
* When should I use this?
* Install
* Use
* API
* [fault(format?[, values…])](#faultformat-values)
* Types
* Compatibility
* Security
* Related
* Contribute
* License

What is this?

This package adds printf-like interpolation to errors.

When should I use this?

This package useful when you frequently display parameters in error messages
and manual string concatenation is becoming verbose.

Install

This package is [ESM only][esm].
In Node.js (version 12.20+, 14.14+, or 16.0+), install with [npm][]:

``sh
npm install fault
`

In Deno with [Skypack][]:

`js
import {fault} from 'https://cdn.skypack.dev/fault@2?dts'
`

In browsers with [Skypack][]:

`html

`

Use

`js
import {fault} from 'fault'

throw fault('Hello %s!', 'Eric')
`

Yields:

`text
Error: Hello Eric!
at FormattedError (~/node_modules/fault/index.js:30:12)
at Object. (~/example.js:3:7)
…
`

Or, format a float in a type error:

`js
import {fault} from 'fault'

throw fault.type('Who doesn’t like %f? 🍰', Math.PI)
`

Yields:

`text
TypeError: Who doesn’t like 3.141593? 🍰
at Function.FormattedError [as type] (~/node_modules/fault/index.js:30:12)
at Object. (~/example.js:3:7)
`

API

This package exports the following identifiers: fault and create.
There is no default export.

$3

Create an error with a printf-like formatted message.

###### Parameters

* format (string, optional)
— template string
values (, optional)
— values to render in format

###### Returns

An [Error][error] instance.

###### Formatters

The following formatters are supported in format:

* %s — string
* %b — binary
* %c — character
* %d — decimal
* %f — floating point
* %o — octal
* %x — lowercase hexadecimal
* %X — uppercase hexadecimal
* % followed by any other character, prints that character

See [samsonjs/format][fmt] for argument parsing.

###### Other errors

* fault.eval(format?[, values…]) — [EvalError][]
* fault.range(format?[, values…]) — [RangeError][]
* fault.reference(format?[, values…]) — [ReferenceError][]
* fault.syntax(format?[, values…]) — [SyntaxError][]
* fault.type(format?[, values…]) — [TypeError][]
* fault.uri(format?[, values…]) — [URIError][]

#### create(Constructor)

Factory to create instances of ErrorConstructor with support for formatting.
Used internally to wrap the global error constructors and exposed for custom
errors.
Returns a function just like fault.

Types

This package is fully typed with [TypeScript][].
There are no extra exported types.

Compatibility

This package is at least compatible with all maintained versions of Node.js.
As of now, that is Node.js 12.20+, 14.14+, and 16.0+.
It also works in Deno and modern browsers.

Security

This package is safe.

Related

* wooorm/bail`
— throw if given an error

Contribute

Yes please!
See [How to Contribute to Open Source][contribute].

License

[MIT][license] © [Titus Wormer][author]

[build-badge]: https://github.com/wooorm/fault/workflows/main/badge.svg

[build]: https://github.com/wooorm/fault/actions

[coverage-badge]: https://img.shields.io/codecov/c/github/wooorm/fault.svg

[coverage]: https://codecov.io/github/wooorm/fault

[downloads-badge]: https://img.shields.io/npm/dm/fault.svg

[downloads]: https://www.npmjs.com/package/fault

[size-badge]: https://img.shields.io/bundlephobia/minzip/fault.svg

[size]: https://bundlephobia.com/result?p=fault

[npm]: https://docs.npmjs.com/cli/install

[skypack]: https://www.skypack.dev

[license]: license

[author]: https://wooorm.com

[esm]: https://gist.github.com/sindresorhus/a39789f98801d908bbc7ff3ecc99d99c

[typescript]: https://www.typescriptlang.org

[contribute]: https://opensource.guide/how-to-contribute/

[fmt]: https://github.com/samsonjs/format

[error]: https://developer.mozilla.org/JavaScript/Reference/Global_Objects/Error

[evalerror]: https://developer.mozilla.org/JavaScript/Reference/Global_Objects/EvalError

[rangeerror]: https://developer.mozilla.org/JavaScript/Reference/Global_Objects/RangeError

[referenceerror]: https://developer.mozilla.org/JavaScript/Reference/Global_Objects/ReferenceError

[syntaxerror]: https://developer.mozilla.org/JavaScript/Reference/Global_Objects/SyntaxError

[typeerror]: https://developer.mozilla.org/JavaScript/Reference/Global_Objects/TypeError

[urierror]: https://developer.mozilla.org/JavaScript/Reference/Global_Objects/URIError.