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https://github.com/prettier/prettier-eslint

Code :arrow_right: prettier :arrow_right: eslint --fix :arrow_right: Formatted Code :sparkles:
https://github.com/prettier/prettier-eslint
eslint formatter hacktoberfest javascript prettier
Last synced: 7 days ago
JSON representation
Code :arrow_right: prettier :arrow_right: eslint --fix :arrow_right: Formatted Code :sparkles:
Host: GitHub
URL: https://github.com/prettier/prettier-eslint
Owner: prettier
License: mit
Created: 2017-01-13T05:43:52.000Z (almost 8 years ago)
Default Branch: master
Last Pushed: 2024-04-30T08:17:23.000Z (6 months ago)
Last Synced: 2024-05-01T13:48:57.185Z (6 months ago)
Topics: eslint, formatter, hacktoberfest, javascript, prettier
Language: JavaScript
Homepage: http://npm.im/prettier-eslint
Size: 524 KB
Stars: 3,931
Watchers: 31
Forks: 171
Open Issues: 7
Metadata Files:
- Readme: README.md
- Changelog: CHANGELOG.md
- Contributing: CONTRIBUTING.md
- Funding: .github/FUNDING.yml
- License: LICENSE
Awesome Lists containing this project

awesome-github-star - prettier-eslint - -fix :arrow_right: Formatted Code :sparkles: | prettier | 3853 | (JavaScript)
README

        # prettier-eslint

Formats your JavaScript using [`prettier`][prettier] followed by [`eslint --fix`][eslint]

[![Build Status][build-badge]][build]

[![Code Coverage][coverage-badge]][coverage]

[![version][version-badge]][package] [![downloads][downloads-badge]][npm-stat]

[![MIT License][license-badge]][license]

[![All Contributors](https://img.shields.io/badge/all_contributors-26-orange.svg?style=flat-square)](#contributors-)

[![PRs Welcome][prs-badge]][prs] [![Donate][donate-badge]][donate]

[![Code of Conduct][coc-badge]][coc] [![Roadmap][roadmap-badge]][roadmap]

[![Examples][examples-badge]][examples]

[![Watch on GitHub][github-watch-badge]][github-watch]

[![Star on GitHub][github-star-badge]][github-star]

[![Tweet][twitter-badge]][twitter]

## The problem

The [`fix`][fix] feature of [`eslint`][eslint] is pretty great and can

auto-format/fix much of your code according to your ESLint config.

[`prettier`][prettier] is a more powerful automatic formatter. One of the nice

things about prettier is how opinionated it is. Unfortunately, it's not

opinionated enough and/or some opinions differ from my own. So after prettier

formats the code, I start getting linting errors.

## This solution

This formats your code via `prettier`, and then passes the result of that to

`eslint --fix`. This way you can get the benefits of `prettier`'s superior

formatting capabilities, but also benefit from the configuration capabilities of

`eslint`.

> For files with an extension of `.css`, `.less`, `.scss`, or `.json` this only

> runs `prettier` since `eslint` cannot process those.

## Installation

This module is distributed via [npm][npm] which is bundled with [node][node] and

should be installed as one of your project's `devDependencies`:

```

npm install --save-dev prettier-eslint

```

## Usage

### Example

```javascript

const format = require('prettier-eslint');

// notice, no semicolon in the original text

const sourceCode = 'const {foo} = bar';

const options = {

  text: sourceCode,

  eslintConfig: {

    parserOptions: {

      ecmaVersion: 7

    },

    rules: {

      semi: ['error', 'never']

    }

  },

  prettierOptions: {

    bracketSpacing: true

  },

  fallbackPrettierOptions: {

    singleQuote: false

  }

};

const formatted = await format(options);

// notice no semicolon in the formatted text

formatted; // const { foo } = bar

```

### options

#### text (String)

The source code to format.

#### filePath (?String)

The path of the file being formatted can be used to override `eslintConfig`

(eslint will be used to find the relevant config for the file).

#### eslintConfig (?Object)

The config to use for formatting with ESLint. Can be overridden with `filePath`.

#### prettierOptions (?Object)

The options to pass for formatting with `prettier`. If not provided,

`prettier-eslint` will attempt to create the options based on the `eslintConfig`

(whether that's provided or derived via `filePath`). You can also provide _some_

of the options and have the remaining options derived via your eslint config.

This is useful for options like `parser`.

**NOTE:** these options _override_ the eslint config. If you want the fallback

options to be used only in the case that the rule cannot be inferred from

eslint, see "fallbackPrettierOptions" below.

#### fallbackPrettierOptions (?Object)

The options to pass for formatting with `prettier` if `prettier-eslint` is not

able to create the options based on the the `eslintConfig` (whether that's

provided or derived via `filePath`). These options will only be used in the case

that the corresponding eslint rule cannot be found and the prettier option has

not been manually defined in `prettierOptions`. If the fallback is not given,

`prettier-eslint` will just use the default `prettier` value in this scenario.

#### logLevel (?Enum: ['trace', 'debug', 'info', 'warn', 'error', 'silent'])

`prettier-eslint` does quite a bit of logging if you want it to. Pass this to

set the number of logs you want to see. Default is `process.env.LOG_LEVEL || 'warn'`.

#### eslintPath (?String)

By default, `prettier-eslint` will try to find the relevant `eslint` (and

`prettier`) module based on the `filePath`. If it cannot find one, then it will

use the version that `prettier-eslint` has installed locally. If you'd like to

specify a path to the `eslint` module you would like to have `prettier-eslint`

use, then you can provide the full path to it with the `eslintPath` option.

#### prettierPath (?String)

This is basically the same as `eslintPath` except for the `prettier` module.

#### prettierLast (?Boolean)

By default, `prettier-eslint` will run `prettier` first, then `eslint --fix`.

This is great if you want to use `prettier`, but override some of the styles you

don't like using `eslint --fix`.

An alternative approach is to use different tools for different concerns. If you

provide `prettierLast: true`, it will run `eslint --fix` first, then `prettier`.

This allows you to use `eslint` to look for bugs and/or bad practices, and use

`prettier` to enforce code style.

### throws

`prettier-eslint` will **only** propagate _parsing_ errors when either `prettier` or `eslint` fails. In addition to propagating the errors, it will also log a specific message indicating what it was doing at the time of the failure.

**Note:** `format` will not show any message regarding broken rules in either `prettier` or `eslint`.

## Capturing ESLint messages

```javascript

const {analyze} = require("prettier-eslint");

const text = 'var x = 0;';

const result = await analyze({

  text,

  eslintConfig: {

    rules: { 'no-var': 'error' }

  }

})    

console.log(result.messages);

```

produces on the console

```

[{

  ruleId: 'no-var',

  severity: 2,

  message: 'Unexpected var, use let or const instead.',

  line: 1,

  column: 1,

  nodeType: 'VariableDeclaration',

  messageId: 'unexpectedVar',

  endLine: 1,

  endColumn: 11

}]

```

The additional export `analyze` is identical to `format` except that it

returns a simple object with properties `output` giving the exact string

that `format` would return, and `messages` giving the array of message

descriptions (with the structure shown above) produced by the `eslint`

analysis of the code. You may use `analyze` in place of `format` if you

would like to perform the formatting but also capture any errors that

`eslint` may notice.

## Technical details

> Code ➡️ prettier ➡️ eslint --fix ➡️ Formatted Code ✨

### inferring prettierOptions via eslintConfig

The `eslintConfig` and `prettierOptions` can each be provided as an argument. If

the `eslintConfig` is not provided, then `prettier-eslint` will look for them

based on the `fileName` (if no `fileName` is provided then it uses

`process.cwd()`). Once `prettier-eslint` has found the `eslintConfig`, the

`prettierOptions` are inferred from the `eslintConfig`. If some of the

`prettierOptions` have already been provided, then `prettier-eslint` will only

infer the remaining options. This inference happens in `src/utils.js`.

**An important thing to note** about this inference is that it may not support

your specific eslint config. So you'll want to check `src/utils.js` to see how

the inference is done for each option (what rule(s) are referenced, etc.) and

[make a pull request][prs] if your configuration is supported.

**Defaults** if you have all of the relevant ESLint rules disabled (or have

ESLint disabled entirely via `/* eslint-disable */` then prettier options will

fall back to the `prettier` defaults:

```javascript

{

  printWidth: 80,

  tabWidth: 2,

  singleQuote: false,

  trailingComma: 'none',

  bracketSpacing: true,

  semi: true,

  useTabs: false,

  // prettier-eslint doesn't currently support

  // inferring these two (Pull Requests welcome):

  parser: 'babylon',

  bracketSameLine: false,

}

```

## Troubleshooting

### debugging issues

There is a lot of logging available with `prettier-eslint`. When debugging, you

can use one of the

[`logLevel`](#loglevel-enum-trace-debug-info-warn-error-silent)s to get a better

idea of what's going on. If you're using `prettier-eslint-cli` then you can use

the `--log-level trace`, if you're using [the Atom plugin][atom-plugin], then

you can [open the developer tools][atom-dev-tools] and enter:

`process.env.LOG_LEVEL = 'trace'` in the console, then run the format. You'll

see a bunch of logs that should help you determine whether the problem is

`prettier`, `eslint --fix`, how `prettier-eslint` infers your `prettier`

options, or any number of other things. You will be asked to do this before

filing issues, so please do :smile:

> NOTE: When you're doing this, it's recommended that you only run this on a

> single file because there are a LOT of logs :)

### eslint-disable-line

While using `// eslint-disable-line`, sometimes you may get linting errors after

the code has been processed by this module. That is because `prettier` changes

this:

```js

// prettier-ignore

if (x) { // eslint-disable-line

}

```

to this:

```js

if (x) {

  // eslint-disable-line

}

```

And the `eslint --fix` wont change it back. You can notice that `// eslint-disable-line` has moved to a new line. To work around this issue, you can

use `//eslint-disable-next-line` instead of `// eslint-disable-line` like this:

```js

// eslint-disable-next-line

if (x) {

}

```

## Inspiration

- [`prettier`][prettier]

- [`eslint`][eslint]

## Other Solutions

None that I'm aware of. Feel free to file a PR if you know of any other

solutions.

## Related

- [`prettier-eslint-cli`](https://github.com/prettier/prettier-eslint-cli) -

  Command Line Interface

- [`prettier-atom`][atom-plugin] - Atom plugin (check the "ESlint integration"

  checkbox in settings)

- [`vs-code-prettier-eslint`][vscode-plugin] - Visual Studio Code plugin

- [`eslint-plugin-prettier`](https://github.com/not-an-aardvark/eslint-plugin-prettier) -

  ESLint plugin. While prettier-eslint uses `eslint --fix` to change the output of `prettier`, eslint-plugin-prettier keeps the `prettier` output as-is and integrates it with the regular ESLint workflow.

- [`prettier-eslint-webpack-plugin`](https://github.com/danielterwiel/prettier-eslint-webpack-plugin) -

  Prettier ESlint Webpack Plugin

## Contributors

Thanks goes to these people ([emoji key][emojis]):

  

    

      
_{Kent C. Dodds}
💻 📖 🚇 ⚠️

      
_{Gyandeep Singh}
👀

      
_{Igor Pnev}
🐛

      
_{Benjamin Tan}
💬 👀

      
_{Eric McCormick}
💻 📖 ⚠️

      
_{Simon Lydell}
📖

      
_{Tom McKearney}
📖 💡

    

    

      
_{Patrik Åkerstrand}
💻

      
_{Lochlan Bunn}
💻

      
_{Daniël Terwiel}
🔌 🔧

      
_{Robin Malfait}
🔧

      
_{Michael McDermott}
💻

      
_{Adam Stankiewicz}
💻

      
_{Stephen John Sorensen}
💻

    

    

      
_{Brian Di Palma}
🐛 💻

      
_{Rob Wise}
📖 💻

      
_{Patryk Peas}
🐛 💻 ⚠️

      
_{Thijs Koerselman}
🐛 💻 ⚠️

      
_{Enrique Caballero}
🐛 💻

      
_{Łukasz Moroz}
🐛 ⚠️

      
_{Simon Fridlund}
💬 🐛 💻 📖 💡 🤔 🚇 🔌 👀 📢 ⚠️ 🔧 ✅

    

    

      
_{Oliver Joseph Ash}
🐛 💻

      
_{Mark Palfreeman}
📖

      
_{Alex Taylor}
💻 ⚠️

      
_{Xianming Zhong}
⚠️

      
_{Lewis Liu}
💻

      
_{Hamza Hamidi}
💻 🤔 🚧 🔧 👀

      
_{Rajiv Ranjan Singh}
💻

    

    

      
_Igor
🚧

      
_{Rebecca Vest}
💻

      
_{Chris Bobbe}
🐛 💻

      
_JounQin
💬 💻 🎨 📖 🤔 🚇 🚧 🔌 📆 👀 ⚠️ 🔧

      
_{Jonathan Rehm}
💻

      
_{Glen Whitney}
💻

    

  

This project follows the [all-contributors][all-contributors] specification.

Contributions of any kind welcome!

## LICENSE

MIT

[prettier]: https://github.com/jlongster/prettier

[eslint]: http://eslint.org/

[fix]: http://eslint.org/docs/user-guide/command-line-interface#fix

[npm]: https://www.npmjs.com/

[node]: https://nodejs.org

[build-badge]: https://img.shields.io/github/actions/workflow/status/prettier/prettier-eslint/ci.yml?style=flat-square

[build]: https://github.com/prettier/prettier-eslint/actions/workflows/ci.yml

[coverage-badge]: https://img.shields.io/codecov/c/github/prettier/prettier-eslint.svg?style=flat-square

[coverage]: https://codecov.io/github/prettier/prettier-eslint

[version-badge]: https://img.shields.io/npm/v/prettier-eslint.svg?style=flat-square

[package]: https://www.npmjs.com/package/prettier-eslint

[downloads-badge]: https://img.shields.io/npm/dm/prettier-eslint.svg?style=flat-square

[npm-stat]: http://npm-stat.com/charts.html?package=prettier-eslint&from=2016-04-01

[license-badge]: https://img.shields.io/npm/l/prettier-eslint.svg?style=flat-square

[license]: https://github.com/prettier/prettier-eslint/blob/master/other/LICENSE

[prs-badge]: https://img.shields.io/badge/PRs-welcome-brightgreen.svg?style=flat-square

[prs]: http://makeapullrequest.com

[donate-badge]: https://img.shields.io/badge/$-support-green.svg?style=flat-square

[donate]: https://www.paypal.me/zimme

[coc-badge]: https://img.shields.io/badge/code%20of-conduct-ff69b4.svg?style=flat-square

[coc]: https://github.com/prettier/prettier-eslint/blob/master/other/CODE_OF_CONDUCT.md

[roadmap-badge]: https://img.shields.io/badge/%F0%9F%93%94-roadmap-CD9523.svg?style=flat-square

[roadmap]: https://github.com/prettier/prettier-eslint/blob/master/other/ROADMAP.md

[examples-badge]: https://img.shields.io/badge/%F0%9F%92%A1-examples-8C8E93.svg?style=flat-square

[examples]: https://github.com/prettier/prettier-eslint/blob/master/other/EXAMPLES.md

[github-watch-badge]: https://img.shields.io/github/watchers/prettier/prettier-eslint.svg?style=social

[github-watch]: https://github.com/prettier/prettier-eslint/watchers

[github-star-badge]: https://img.shields.io/github/stars/prettier/prettier-eslint.svg?style=social

[github-star]: https://github.com/prettier/prettier-eslint/stargazers

[twitter]: https://twitter.com/intent/tweet?text=Check%20out%20prettier-eslint!%20https://github.com/prettier/prettier-eslint%20%F0%9F%91%8D

[twitter-badge]: https://img.shields.io/twitter/url/https/github.com/prettier/prettier-eslint.svg?style=social

[emojis]: https://github.com/kentcdodds/all-contributors#emoji-key

[all-contributors]: https://github.com/kentcdodds/all-contributors

[atom-plugin]: https://github.com/prettier/prettier-atom

[atom-dev-tools]: https://discuss.atom.io/t/how-to-make-developer-tools-appear/16232

[vscode-plugin]: https://github.com/idahogurl/vs-code-prettier-eslint