---
tags: Frontends
---
Eslint
===

## Step 1: Install

yarn add eslint --dev
yarn add eslint-plugin-react eslint-plugin-css-modules eslint-config-airbnb eslint-plugin-import eslint-plugin-react-hooks eslint-plugin-jsx-a11y @typescript-eslint/eslint-plugin @typescript-eslint/parser -D

-- init eslint configration
./node_modules/.bin/eslint --init

Choose the option
1. To check syntax, find problems, and enforce code style
2. JavaScript modules (import/export)
3. None of these (react/ vue)
4. Yes for typescript.
5. Browser (if for frontend) - (node for backend).
6. Use a popular style guide: `airbnb`
7. JavaScript -- format for eslint config
8. Would you like to install them now with npm? › `No` -> if you use `yarn`

## Step 2: Config Eslint
- Install Eslint extension
- Open setting (Json) of VS code: add configs `settings.json`

"editor.codeActionsOnSave": {
  "source.fixAll.eslint": true
},
"eslint.validate": ["javascript"],
"editor.formatOnSave": true,

- Open `package.json`:

"scripts": {
    "lint": "eslint \"./src/**/*.{ts,tsx}\"",
    "lintcss": "stylelint \"./src/**/*.{scss,css}\"",
},

## Step 3: Add rules:
Ref: https://eslint.org/docs/rules/
1. if you don't want to produce any error messages: `off` | `warn` | `error`
`"no-console": "off",`
2. Double quotes:
`"quotes": ["error", "double"],`
3. Indent:
`"indent": ["error", 4],`

Sample: `eslintrc.js`

module.exports = {
    env: {
        browser: true,
        es6: true,
    },
    parser: '@typescript-eslint/parser',
    parserOptions: {
        ecmaFeatures: {
            jsx: true,
        },
        // project: './tsconfig.json',
        ecmaVersion: 2018,
        sourceType: 'module',
    },
    extends: [
        'plugin:react/recommended',
        'plugin:@typescript-eslint/recommended',
        'airbnb',
        'plugin:import/errors',
        'plugin:import/warnings',
        'plugin:css-modules/recommended',
    ],
    globals: {
        Atomics: 'readonly',
        SharedArrayBuffer: 'readonly',
    },
    plugins: [
        'react',
        'react-hooks',
        '@typescript-eslint',
        'css-modules',
    ],
    rules: {
        'max-len': ['error', { code: 120 }],
        'no-console': 'off',
        indent: ['error', 4, { SwitchCase: 1 }],
        'no-plusplus': ['warn', { allowForLoopAfterthoughts: true }],
        'class-methods-use-this': 'off',
        'react/jsx-indent': ['error', 4],
        'react/jsx-indent-props': ['error', 4],
        'react/jsx-filename-extension': ['error', { extensions: ['.ts', '.tsx'] }],
        'react/state-in-constructor': ['warn', 'never'],
        'react/destructuring-assignment': ['warn', 'always', { ignoreClassFields: true }],
        'import/prefer-default-export': 'off',
        'import/default': 'off',
        'import/order': ['warn', { alphabetize: { order: 'asc' } }],
        'import/extensions': [
            'error',
            'ignorePackages',
            {
                js: 'never',
                jsx: 'never',
                ts: 'never',
                tsx: 'never',
                mjs: 'never',
            },
        ],
        'react-hooks/rules-of-hooks': 'error',
        'react-hooks/exhaustive-deps': 'warn',
        'react/prop-types': 'off',
        'react/jsx-props-no-spreading': 'off',
        'spaced-comment': ['error', 'always', {
            markers: ['/'],
        }],
        'no-unused-expressions': 'off',
        '@typescript-eslint/no-explicit-any': 'off',
        '@typescript-eslint/explicit-module-boundary-types': ['error', { allowArgumentsExplicitlyTypedAsAny: true }],
        '@typescript-eslint/no-non-null-assertion': 'off',
        '@typescript-eslint/no-use-before-define': ['error'],
        '@typescript-eslint/no-unused-vars': 'error',
        '@typescript-eslint/no-shadow': 'error',
        'no-continue': 'off',
        'react/require-default-props': 'off',
        'no-use-before-define': 'off',
        'no-undef': 'off',
        'no-unused-vars': 'off',
        'no-shadow': 'off',
        'react/jsx-uses-react': 'off',
        'react/react-in-jsx-scope': 'off',
    },
    settings: {
        'import/resolver': {
            node: {
                extensions: ['.js', '.jsx', '.ts', '.tsx'],
            },
        },
    },
    overrides: [
        {
            files: [
                '**/*.test.{ts,tsx}',
            ],
            env: {
                jest: true,
            },
            rules: {
                'import/no-extraneous-dependencies': 'off',
            },
        },
    ],
};