@merlinalexhjp/eslint-config v2.4.0

@merlinalexhjp/eslint-config

• Single quotes, no semi
• Auto fix for formatting (aimed to be used standalone without Prettier)
• Designed to work with TypeScript, JSX, Vue out-of-box
• Lints also for json, yaml, markdown
• Sorted imports, dangling commas
• Reasonable defaults, best practices, only one-line of config
• Respects .gitignore by default
• ESLint Flat config, compose easily!
• Using ESLint Stylistic
• Style principle: Minimal for reading, stable for diff, consistent

Usage

Install

pnpm i -D eslint @merlinalexhjp/eslint-config

Create config file

With "type": "module" in package.json (recommended):

// eslint.config.js
import merlin from '@merlinalexhjp/eslint-config'

export default merlin()

With CJS:

// eslint.config.js
const merlin = require('@merlinalexhjp/eslint-config').default

module.exports = merlin()

Note that .eslintignore no longer works in Flat config, see customization for more details.

Add script for package.json

For example:

{
  "scripts": {
    "lint": "eslint .",
    "lint:fix": "eslint . --fix"
  }
}

VS Code support (auto fix)

Install VS Code ESLint extension

Add the following settings to your .vscode/settings.json:

{
  // Enable the ESlint flat config support
  "eslint.experimental.useFlatConfig": true,

  // Disable the default formatter, use eslint instead
  "prettier.enable": false,
  "editor.formatOnSave": false,

  // Auto fix
  "editor.codeActionsOnSave": {
    "source.fixAll.eslint": "explicit",
    "source.organizeImports": "never"
  },

  // Silent the stylistic rules in you IDE, but still auto fix them
  "eslint.rules.customizations": [
    { "rule": "style/*", "severity": "off" },
    { "rule": "*-indent", "severity": "off" },
    { "rule": "*-spacing", "severity": "off" },
    { "rule": "*-spaces", "severity": "off" },
    { "rule": "*-order", "severity": "off" },
    { "rule": "*-dangle", "severity": "off" },
    { "rule": "*-newline", "severity": "off" },
    { "rule": "*quotes", "severity": "off" },
    { "rule": "*semi", "severity": "off" }
  ],

  // Enable eslint for all supported languages
  "eslint.validate": [
    "javascript",
    "javascriptreact",
    "typescript",
    "typescriptreact",
    "vue",
    "html",
    "markdown",
    "json",
    "jsonc",
    "yaml"
  ]
}

Customization

Since v1.0, we migrated to ESLint Flat config. It provides much better organization and composition.

Normally you only need to import the merlin preset:

// eslint.config.js
import merlin from '@merlinalexhjp/eslint-config'

export default merlin()

And that's it! Or you can configure each integration individually, for example:

// eslint.config.js
import merlin from '@merlin/eslint-config'

export default merlin({
  // Enable stylistic formatting rules
  // stylistic: true,

  // Or customize the stylistic rules
  stylistic: {
    indent: 2, // 4, or 'tab'
    quotes: 'single', // or 'double'
  },

  // TypeScript and Vue are auto-detected, you can also explicitly enable them:
  typescript: true,
  vue: true,

  // Disable jsonc and yaml support
  jsonc: false,
  yaml: false,

  // `.eslintignore` is no longer supported in Flat config, use `ignores` instead
  ignores: [
    './fixtures',
    // ...globs
  ]
})

The merlin factory function also accepts any number of arbitrary custom config overrides:

// eslint.config.js
import merlin from '@merlin/eslint-config'

export default merlin(
  {
    // Configures for merlin's config
  },

  // From the second arguments they are ESLint Flat Configs
  // you can have multiple configs
  {
    files: ['**/*.ts'],
    rules: {},
  },
  {
    rules: {},
  },
)

Rules Overrides

Certain rules would only be enabled in specific files, for example, ts/* rules would only be enabled in .ts files and vue/* rules would only be enabled in .vue files. If you want to override the rules, you need to specify the file extension:

// eslint.config.js
import merlin from '@merlinalexhjp/eslint-config'

export default merlin(
  { vue: true, typescript: true },
  {
    // Remember to specify the file glob here, otherwise it might cause the vue plugin to handle non-vue files
    files: ['**/*.vue'],
    rules: {
      'vue/operator-linebreak': ['error', 'before'],
    },
  },
  {
    // Without `files`, they are general rules for all files
    rules: {
      'style/semi': ['error', 'never'],
    },
  }
)

We also provided an overrides options to make it easier:

// eslint.config.js
import merlin from '@merlinalexhjp/eslint-config'

export default merlin({
  overrides: {
    vue: {
      'vue/operator-linebreak': ['error', 'before'],
    },
    typescript: {
      'ts/consistent-type-definitions': ['error', 'interface'],
    },
    yaml: {},
    // ...
  }
})

Optional Configs

React

We do include configs for React. But due to the install size of React plugins we didn't include the dependencies by default.

To enable React support, need to explicitly turn it on:

// eslint.config.js
import antfu from '@antfu/eslint-config'

export default antfu({
  react: true,
})

Running npx eslint should prompt you to install the required dependencies, otherwise you can install them manually:

npm i -D eslint-plugin-react eslint-plugin-react-hooks eslint-plugin-react-refresh