.eslintrc.js

module.exports = {
  env: {
    browser: true,
    commonjs: true,
    es2020: true,
    node: true,
    mocha: true
  },
  globals: {},
  parser: 'babel-eslint',
  parserOptions: {
    ecmaVersion: 2020,
  },
  plugins: [
    'node',
    'mocha',
    'jsdoc',
    'babel',
  ],
  extends: [
    'eslint:recommended',
    'plugin:jsdoc/recommended',
    'plugin:node/recommended',
  ],
  overrides: [{
    files: ['test/**/*.test.js'],
    extends: [
      'plugin:mocha/recommended',
    ],
    rules: {
      'prefer-arrow-callback': 'off',
      'node/no-unpublished-require': 'off',
    }
  }],
  rules: {
    'linebreak-style': ['error', 'unix'],

    // babel overrides
    'babel/new-cap': ['error', { newIsCap: true, capIsNew: false, properties: true }],
    'babel/camelcase': ['error', { properties: 'never' }],
    'babel/no-invalid-this': 1,
    'babel/object-curly-spacing': ['error', 'always'],
    'babel/quotes': ['error', 'single', { avoidEscape: true }],
    'babel/semi': ['error', 'never'],
    'babel/no-unused-expressions': ['error', { allowShortCircuit: true, allowTernary: true, allowTaggedTemplates: true }],
    'babel/valid-typeof': ['error', { requireStringLiterals: true }],
    'new-cap': 0,
    'no-invalid-this': 0,
    'object-curly-spacing': 0,
    'quotes': 0,
    'semi': 0,
    'no-unused-expressions': 0,
    'valid-typeof': 0,

    // -- test to see if necessary
    'accessor-pairs': 'error',
    'array-bracket-spacing': ['error', 'never'],
    'arrow-spacing': ['error', { before: true, after: true }],
    'block-spacing': ['error', 'always'],
    'brace-style': ['error', '1tbs', { allowSingleLine: true }],
    'comma-dangle': ['error', 'only-multiline'],
    'comma-spacing': ['error', { before: false, after: true }],
    'comma-style': ['error', 'last'],
    'computed-property-spacing': ['error', 'never'],
    'constructor-super': 'error',
    'curly': ['error', 'multi', 'consistent'],
    'dot-location': ['error', 'property'],
    'dot-notation': ['error', { allowKeywords: true }],
    'eol-last': 'error',
    'eqeqeq': ['error', 'always', { null: 'ignore' }],
    'func-call-spacing': ['error', 'never'],
    'generator-star-spacing': ['error', { before: true, after: true }],
    'handle-callback-err': ['error', '^(err|error)$'],
    'indent': ['error', 2, {
      ArrayExpression: 1,
      CallExpression: { arguments: 1 },
      FunctionDeclaration: { parameters: 1, body: 1 },
      FunctionExpression: { parameters: 1, body: 1 },
      ImportDeclaration: 1,
      MemberExpression: 1,
      ObjectExpression: 1,
      SwitchCase: 1,
      VariableDeclarator: 1,
      flatTernaryExpressions: false,
      ignoreComments: false,
      ignoredNodes: ['TemplateLiteral *'],
      outerIIFEBody: 1,
    }],
    'key-spacing': ['error', { beforeColon: false, afterColon: true }],
    'keyword-spacing': ['error', { before: true, after: true }],
    'lines-between-class-members': ['error', 'always', { exceptAfterSingleLine: true }],
    'new-parens': 'error',
    'no-array-constructor': 'error',
    'no-async-promise-executor': 'error',
    'no-caller': 'error',
    'no-case-declarations': 'error',
    'no-class-assign': 'error',
    'no-compare-neg-zero': 'error',
    'no-cond-assign': 'error',
    'no-const-assign': 'error',
    'no-constant-condition': ['error', { checkLoops: false }],
    'no-control-regex': 'error',
    'no-debugger': 'error',
    'no-delete-var': 'error',
    'no-dupe-args': 'error',
    'no-dupe-class-members': 'error',
    'no-dupe-keys': 'error',
    'no-duplicate-case': 'error',
    'no-empty-character-class': 'error',
    'no-empty-pattern': 'error',
    'no-eval': 'error',
    'no-ex-assign': 'error',
    'no-extend-native': 'error',
    'no-extra-bind': 'error',
    'no-extra-boolean-cast': 'error',
    'no-extra-parens': ['error', 'functions'],
    'no-fallthrough': 'error',
    'no-floating-decimal': 'error',
    'no-func-assign': 'error',
    'no-global-assign': 'error',
    'no-implied-eval': 'error',
    'no-inner-declarations': ['error', 'functions'],
    'no-invalid-regexp': 'error',
    'no-irregular-whitespace': 'error',
    'no-iterator': 'error',
    'no-labels': ['error', { allowLoop: false, allowSwitch: false }],
    'no-lone-blocks': 'error',
    'no-misleading-character-class': 'error',
    'no-prototype-builtins': 'error',
    'no-useless-catch': 'error',
    'no-mixed-operators': ['error', {
      groups: [
        ['==', '!=', '===', '!==', '>', '>=', '<', '<='],
        ['&&', '||'],
        ['in', 'instanceof']
      ],
      allowSamePrecedence: true
    }],
    'no-mixed-spaces-and-tabs': 'error',
    'no-multi-spaces': 'error',
    'no-multi-str': 'error',
    'no-multiple-empty-lines': ['error', { max: 1, maxEOF: 0 }],
    'no-negated-in-lhs': 'error',
    'no-new': 'error',
    'no-new-func': 'error',
    'no-new-object': 'error',
    'no-new-require': 'error',
    'no-new-symbol': 'error',
    'no-new-wrappers': 'error',
    'no-obj-calls': 'error',
    'no-octal': 'error',
    'no-octal-escape': 'error',
    'no-path-concat': 'error',
    'no-proto': 'error',
    'no-redeclare': ['error', { builtinGlobals: false }],
    'no-regex-spaces': 'error',
    'no-return-assign': ['error', 'except-parens'],
    'no-self-assign': ['error', { props: true }],
    'no-self-compare': 'error',
    'no-sequences': 'error',
    'no-shadow-restricted-names': 'error',
    'no-sparse-arrays': 'error',
    'no-tabs': 'error',
    'no-template-curly-in-string': 'error',
    'no-this-before-super': 'error',
    'no-throw-literal': 'error',
    'no-trailing-spaces': 'error',
    'no-undef': 'error',
    'no-undef-init': 'error',
    'no-unexpected-multiline': 'error',
    'no-unmodified-loop-condition': 'error',
    'no-unneeded-ternary': ['error', { defaultAssignment: false }],
    'no-unreachable': 'error',
    'no-unsafe-finally': 'error',
    'no-unsafe-negation': 'error',
    'no-unused-vars': ['error', { vars: 'all', args: 'none', ignoreRestSiblings: true }],
    'no-use-before-define': ['error', { functions: false, classes: false, variables: false }],
    'no-useless-call': 'error',
    'no-useless-computed-key': 'error',
    'no-useless-constructor': 'error',
    'no-useless-escape': 'error',
    'no-useless-rename': 'error',
    'no-useless-return': 'error',
    'no-void': 'error',
    'no-whitespace-before-property': 'error',
    'no-with': 'error',
    'object-curly-newline': ['error', { multiline: true, consistent: true }],
    'object-property-newline': ['error', { allowMultiplePropertiesPerLine: true }],
    'one-var': ['error', { initialized: 'never' }],
    'operator-linebreak': ['error', 'after', { overrides: { '?': 'before', ':': 'before', '|>': 'before' } }],
    'padded-blocks': ['error', { blocks: 'never', switches: 'never', classes: 'never' }],
    'prefer-const': ['error', { destructuring: 'all' }],
    'prefer-promise-reject-errors': 'error',
    'quote-props': ['error', 'consistent-as-needed'],
    'rest-spread-spacing': ['error', 'never'],
    'semi-spacing': ['error', { before: false, after: true }],
    'space-before-blocks': ['error', 'always'],
    'space-before-function-paren': ['error', {
      named: 'never',
      anonymous: 'always',
      asyncArrow: 'always',
    }],
    'space-in-parens': ['error', 'never'],
    'space-infix-ops': 'error',
    'space-unary-ops': ['error', { words: true, nonwords: false }],
    'spaced-comment': ['error', 'always', {
      line: { markers: ['*package', '!', '/', ',', '='] },
      block: { balanced: true, markers: ['*package', '!', ',', ':', '::', 'flow-include'], exceptions: ['*'] }
    }],
    'node/no-deprecated-api': 'error',
    'node/process-exit-as-throw': 'error',
    'prefer-arrow-callback': ['error', { allowNamedFunctions: true }],
    'symbol-description': 'error',
    'template-curly-spacing': ['error', 'never'],
    'template-tag-spacing': ['error', 'never'],
    'unicode-bom': ['error', 'never'],
    'use-isnan': 'error',
    'wrap-iife': ['error', 'any', { functionPrototypeMethods: true }],
    'yield-star-spacing': ['error', 'both'],
    'yoda': ['error', 'never'],
  }
}