# ESLint Plugin
[ESLint](https://eslint.org/) plugin including configurations and custom rules for WordPress development.
## Installation
Install the module
```bash
npm install @wordpress/eslint-plugin --save-dev
```
**Note**: This package requires `node` 14.0.0 or later, and `npm` 6.14.4 or later. It is not compatible with older versions.
## Usage
To opt-in to the default configuration, extend your own project's `.eslintrc` file:
```json
{
"extends": [ "plugin:@wordpress/eslint-plugin/recommended" ]
}
```
Refer to the [ESLint documentation on Shareable Configs](http://eslint.org/docs/developer-guide/shareable-configs) for more information.
The `recommended` preset will include rules governing an ES2015+ environment, and includes rules from the [`eslint-plugin-jsdoc`](https://github.com/gajus/eslint-plugin-jsdoc), [`eslint-plugin-jsx-a11y`](https://github.com/jsx-eslint/eslint-plugin-jsx-a11y), [`eslint-plugin-react`](https://github.com/yannickcr/eslint-plugin-react), and other similar plugins.
This preset offers an optional integration with the [`eslint-plugin-prettier`](https://github.com/prettier/eslint-plugin-prettier) package that runs [Prettier](https://prettier.io) code formatter and reports differences as individual ESLint issues. You can activate it by installing the [`prettier`](https://www.npmjs.com/package/prettier) package separately with:
```bash
npm install prettier --save-dev
```
Finally, this ruleset also includes an optional integration with the [`@typescript-eslint/eslint-plugin`](https://github.com/typescript-eslint/typescript-eslint) package that enables ESLint to support [TypeScript](https://www.typescriptlang.org) language. You can activate it by installing the [`typescript`](https://www.npmjs.com/package/typescript) package separately with:
```bash
npm install typescript --save-dev
```
There is also `recommended-with-formatting` ruleset for projects that want to ensure that [Prettier](https://prettier.io) and [TypeScript](https://www.typescriptlang.org) integration is never activated. This preset has the native ESLint code formatting rules enabled instead.
### Rulesets
Alternatively, you can opt-in to only the more granular rulesets offered by the plugin. These include:
- `custom` – custom rules for WordPress development.
- `es5` – rules for legacy ES5 environments.
- `esnext` – rules for ES2015+ environments.
- `i18n` – rules for internationalization.
- `jsdoc` – rules for JSDoc comments.
- `jsx-a11y` – rules for accessibility in JSX.
- `react` – rules for React components.
- `test-e2e` – rules for end-to-end tests written in Puppeteer.
- `test-unit`– rules for unit tests written in Jest.
- `test-playwright` – rules for end-to-end tests written in Playwright.
For example, if your project does not use React, you could consider extending including only the ESNext rules in your project using the following `extends` definition:
```json
{
"extends": [ "plugin:@wordpress/eslint-plugin/esnext" ]
}
```
These rules can be used additively, so you could extend both `esnext` and `custom` rulesets, but omit the `react` and `jsx-a11y` configurations.
The granular rulesets will not define any environment globals. As such, if they are required for your project, you will need to define them yourself.
### Rules
| Rule | Description | Recommended |
| -------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ---------------------------------------------------------------------------------------------- | ----------- |
| [data-no-store-string-literals](https://github.com/WordPress/gutenberg/tree/HEAD/packages/eslint-plugin/docs/rules/data-no-store-string-literals.md) | Discourage passing string literals to reference data stores | |
| [dependency-group](https://github.com/WordPress/gutenberg/tree/HEAD/packages/eslint-plugin/docs/rules/dependency-group.md) | Enforce dependencies docblocks formatting | ✓ |
| [is-gutenberg-plugin](docs/rules/is-gutenberg-plugin.md) | Governs the use of the `process.env.IS_GUTENBERG_PLUGIN` constant | ✓ |
| [no-base-control-with-label-without-id](https://github.com/WordPress/gutenberg/tree/HEAD/packages/eslint-plugin/docs/rules/no-base-control-with-label-without-id.md) | Disallow the usage of BaseControl component with a label prop set but omitting the id property | ✓ |
| [no-unguarded-get-range-at](https://github.com/WordPress/gutenberg/tree/HEAD/packages/eslint-plugin/docs/rules/no-unguarded-get-range-at.md) | Disallow the usage of unguarded `getRangeAt` calls | ✓ |
| [no-unsafe-wp-apis](https://github.com/WordPress/gutenberg/tree/HEAD/packages/eslint-plugin/docs/rules/no-unsafe-wp-apis.md) | Disallow the usage of unsafe APIs from `@wordpress/*` packages | ✓ |
| [no-unused-vars-before-return](https://github.com/WordPress/gutenberg/tree/HEAD/packages/eslint-plugin/docs/rules/no-unused-vars-before-return.md) | Disallow assigning variable values if unused before a return | ✓ |
| [react-no-unsafe-timeout](https://github.com/WordPress/gutenberg/tree/HEAD/packages/eslint-plugin/docs/rules/react-no-unsafe-timeout.md) | Disallow unsafe `setTimeout` in component | |
| [valid-sprintf](https://github.com/WordPress/gutenberg/tree/HEAD/packages/eslint-plugin/docs/rules/valid-sprintf.md) | Enforce valid sprintf usage | ✓ |
| [i18n-ellipsis](https://github.com/WordPress/gutenberg/tree/HEAD/packages/eslint-plugin/docs/rules/i18n-ellipsis.md) | Disallow using three dots in translatable strings | ✓ |
| [i18n-no-collapsible-whitespace](https://github.com/WordPress/gutenberg/tree/HEAD/packages/eslint-plugin/docs/rules/i18n-no-collapsible-whitespace.md) | Disallow collapsible whitespace in translatable strings | ✓ |
| [i18n-no-placeholders-only](https://github.com/WordPress/gutenberg/tree/HEAD/packages/eslint-plugin/docs/rules/i18n-no-placeholders-only.md) | Prevent using only placeholders in translatable strings | ✓ |
| [i18n-no-variables](https://github.com/WordPress/gutenberg/tree/HEAD/packages/eslint-plugin/docs/rules/i18n-no-variables.md) | Enforce string literals as translation function arguments | ✓ |
| [i18n-text-domain](https://github.com/WordPress/gutenberg/tree/HEAD/packages/eslint-plugin/docs/rules/i18n-text-domain.md) | Enforce passing valid text domains | ✓ |
| [i18n-translator-comments](https://github.com/WordPress/gutenberg/tree/HEAD/packages/eslint-plugin/docs/rules/i18n-translator-comments.md) | Enforce adding translator comments | ✓ |
| [i18n-no-flanking-whitespace](https://github.com/WordPress/gutenberg/tree/HEAD/packages/eslint-plugin/docs/rules/i18n-no-flanking-whitespace.md) | Disallow leading or trailing whitespace in translatable strings | |
| [i18n-hyphenated-range](https://github.com/WordPress/gutenberg/tree/HEAD/packages/eslint-plugin/docs/rules/i18n-hyphenated-range.md) | Disallow hyphenated numerical ranges in translatable strings | |
### Legacy
If you are using WordPress' `.jshintrc` JSHint configuration and you would like to take the first step to migrate to an ESLint equivalent it is also possible to define your own project's `.eslintrc` file as:
```json
{
"extends": [ "plugin:@wordpress/eslint-plugin/jshint" ]
}
```
## Contributing to this package
This is an individual package that's part of the Gutenberg project. The project is organized as a monorepo. It's made up of multiple self-contained software packages, each with a specific purpose. The packages in this monorepo are published to [npm](https://www.npmjs.com/) and used by [WordPress](https://make.wordpress.org/core/) as well as other software projects.
To find out more about contributing to this package or Gutenberg as a whole, please read the project's main [contributor guide](https://github.com/WordPress/gutenberg/tree/HEAD/CONTRIBUTING.md).
