!ESLint Slango Eslint Configs (@slango.configs/eslint)

This package exposes eslint configurations for easy setup, the following presets are available:

| Name | Description | Includes |
| -------------------- | --------------------------------------------------------------------------------------------------- | -------------------------------- |
| javascript-node | Intended to be used for tooling javascript files (eg: eslint.confg.js, linte-staged.config.js, ...) | - |
| typescript | Intended to be used for typescript based projects and libraries | javascript-node |
| typescript-node | Intended to be used for typescript based node projects and libraries | javascript-node + typescript |
| typescript-browser | Intended to be used for typescript based browser projects and libraries | javascript-node + typescript |
| typescript-next | Intended to be used for typescript based next.js applications | javascript-node + typescript |

Included plugins/configs

| Name | Available in Preset | Description |
| ---------------------------------------------------------------------------------------------------------------- | ------------------------ | -------------------------------------------------------- |
| @eslint/js recommended | all | @eslint/js official recommended configuration |
| eslint-plugin-eslint-comments recommended | all | Comments from @eslint-community for comments |
| eslint-plugin-perfectionist | all | Configurable sorting rules with tiered strictness levels |
| eslint-plugin-regex recommended | all | Recommended config from regexp-eslint-plugin |
| eslint-plugin-prettier recommended | all | Prettier official eslint plugin's recommended config |
| eslint-plugin-import recommended | all | Prettier official eslint plugin's recommended config |
| typescript-eslint recommendedTypeChecked | all typescript configs | Typescript Eslint type checked recommended config |
| next/core-web-vitals | typescript-next | Next.js official eslint config |

Usage

Add @slango.configs/eslint to your package.json as a dev dependency, then create a eslint.config.js file in the package.

Unless you want to override the default configuration, you can simply extend the configuration as follows:

``js
// eslint.config.js
export { default } from '@slango.configs/eslint/{preset-you-wish-to-use}.js';
`

$3

Perfectionist sorting rules are organized into tiers and can be configured with four levels of strictness:

| Level | Description | Use Case |
| ---------- | -------------------------------------------------- | ---------------------------------------- |
| off | All perfectionist rules disabled | When you want no automatic sorting |
| relaxed | Import/export sorting only (default) | Universally accepted, industry standard |
| moderate | Adds type sorting (interfaces, unions, enums) | Good for type-heavy TypeScript codebases |
| strict | Full sorting including objects, classes, JSX props | Maximum consistency, use with caution |

#### Rule tiers

Tier 1 - Import/Export sorting (relaxed+)

- sort-imports, sort-named-imports, sort-named-exports, sort-exports
- sort-import-attributes, sort-export-attributes, sort-modules

Tier 2 - Type sorting (moderate+)

- sort-union-types, sort-intersection-types, sort-heritage-clauses
- sort-object-types, sort-interfaces, sort-enums

Tier 3 - Full sorting (strict only)

- sort-objects, sort-classes, sort-jsx-props, sort-decorators
- sort-switch-case, sort-variable-declarations, sort-array-includes
- sort-sets, sort-maps

> Note: Tier 3 rules are disabled by default because they can be controversial or break intentional ordering. For example, sort-decorators can break functionality when decorator order matters semantically, and sort-switch-case often disrupts intentional case ordering (common cases first, fallbacks last).

To use a custom level, import the corresponding creator and pass an options object:

`js
// eslint.config.js
import { createTypescriptConfig } from '@slango.configs/eslint/typescript.js';

export default createTypescriptConfig({ perfectionist: 'moderate' });
``

Passing an unknown option or an invalid level throws a descriptive error.

Things to take into account (and possibly review)

- At the time of writing eslint-config-prettier is needed as a dependency to use eslint-plugin-prettier
- eslint-plugin-import-x supports eslint 9 but eslint-plugin-import does not usage comparison
- eslint-import-resolver-node does not seem to play well with monorepo/pattern exports in package.json (thus eslint-import-resolver-typescript is used even for javascript)

Interesting links

- Eslint v9 supported community plugins