eslint-config/packages/common/index.js

module.exports = {
  env: {
    es6: true,
    browser: true,
    node: true,
  },
  extends: [
    'standard',
    'plugin:import/errors',
    'plugin:import/warnings',
    'plugin:unicorn/recommended',
  ],
  plugins: [
    'unicorn',
  ],
  settings: {
    'import/resolver': {
      node: { extensions: ['.js', '.mjs'] },
    },
  },
  rules: {
    // import
    'import/order': 'error',
    'import/first': 'error',
    'import/no-mutable-exports': 'error',
    'import/no-unresolved': 'off',

    // Common
    'semi': [2, 'never'],
    'curly': [2, 'multi-or-nest', 'consistent'],
    'quotes': ['error', 'single'],
    'no-unused-vars': 'warn',
    'no-param-reassign': 'off',
    'array-bracket-spacing': ['error', 'never'],
    'brace-style': ['error', 'stroustrup', { 'allowSingleLine': true }],
    'block-spacing': ['error', 'always'],
    'camelcase': 'off',
    'comma-spacing': ['error', { before: false, after: true }],
    'comma-style': ['error', 'last'],
    'comma-dangle': ['error', 'always-multiline'],
    'no-constant-condition': 'warn',
    'no-debugger': process.env.NODE_ENV === 'production' ? 'error' : 'off',
    'no-console': process.env.NODE_ENV === 'production' ? 'error' : 'off',
    'no-cond-assign': ['error', 'always'],
    'func-call-spacing': ['off', 'never'],
    'key-spacing': ['error', { beforeColon: false, afterColon: true }],
    'indent': ['error', 2, { SwitchCase: 1, VariableDeclarator: 1, outerIIFEBody: 1 }],
    'no-restricted-syntax': [
      'error',
      'DebuggerStatement',
      'ForInStatement',
      'LabeledStatement',
      'WithStatement',
    ],
    'no-spaced-func': 'error',
    'object-curly-spacing': ['error', 'always'],
    'no-return-await': 'off',
    'space-before-function-paren': ['error', 'never'],

    // es6
    'no-var': 'error',
    'prefer-const': ['error', {
      destructuring: 'any',
      ignoreReadBeforeAssign: true,
    }],
    'prefer-arrow-callback': ['error', {
      allowNamedFunctions: false,
      allowUnboundThis: true,
    }],
    'object-shorthand': ['error', 'always', {
      ignoreConstructors: false,
      avoidQuotes: true,
    }],
    'prefer-rest-params': 'error',
    'prefer-spread': 'error',
    'prefer-template': 'error',
    'template-curly-spacing': 'error',
    'arrow-parens': ['error', 'as-needed', { requireForBlockBody: true }],
    'generator-star-spacing': 'off',

    // best-practice
    'array-callback-return': 'error',
    'block-scoped-var': 'error',
    'consistent-return': 'off',
    'complexity': ['off', 11],
    'eqeqeq': ['error', 'allow-null'],
    'no-alert': 'warn',
    'no-case-declarations': 'error',
    'no-multi-spaces': 'error',
    'no-multi-str': 'error',
    'no-with': 'error',
    'no-void': 'error',
    'no-useless-escape': 'error',
    'vars-on-top': 'error',
    'require-await': 'off',
    'no-return-assign': 'off',
    'operator-linebreak': [2, 'before'],

    // unicorns
    // Pass error message when throwing errors
    'unicorn/error-message': 'error',
    // Uppercase regex escapes
    'unicorn/escape-case': 'error',
    // Array.isArray instead of instanceof
    'unicorn/no-array-instanceof': 'error',
    // Prevent deprecated `new Buffer()`
    'unicorn/no-new-buffer': 'error',
    // Keep regex literals safe!
    'unicorn/no-unsafe-regex': 'off',
    // Lowercase number formatting for octal, hex, binary (0x12 instead of 0X12)
    'unicorn/number-literal-case': 'error',
    // ** instead of Math.pow()
    'unicorn/prefer-exponentiation-operator': 'error',
    // includes over indexOf when checking for existence
    'unicorn/prefer-includes': 'error',
    // String methods startsWith/endsWith instead of more complicated stuff
    'unicorn/prefer-starts-ends-with': 'error',
    // textContent instead of innerText
    'unicorn/prefer-text-content': 'error',
    // Enforce throwing type error when throwing error while checking typeof
    'unicorn/prefer-type-error': 'error',
    // Use new when throwing error
    'unicorn/throw-new-error': 'error',
  },
}