.eslintrc.js

'use strict'

// Rules for this project. The first number is the warning level as reported by
// eslint, the rest are settings for the error.

const OFF = 0
const WARNING = 1
const ERROR = 2

module.exports = {
  'parserOptions': {
    'ecmaVersion': 2018,
  },

  // Inherit from eslint's recommended settings
  'extends': 'eslint:recommended',

  // Make these includes available so eslint doesn't complain about it
  'env': {
    'es6': true,
    'node': true,
    'mocha': true,
  },

  'rules': {
    // 2 space indent
    'indent': [
      ERROR,
      2,
    ],
    // Disabled: enforce single quoted strings
    'quotes': [
      OFF,
      'single',
    ],
    // unix style line endings
    'linebreak-style': [
      ERROR,
      'unix',
    ],

    // Disallow semi-colons, except where necessary to disambiguate
    // statements
    // http://eslint.org/docs/rules/semi
    'semi': [WARNING, 'never'],

    // Helps cover some ambiguous semi-colon cases, where auto-inserted
    // semi-colons might make a code portion unreachable unexpectedly
    // http://eslint.org/docs/rules/no-unreachable
    'no-unreachable': [ERROR],

    // Helps cover more semi-colon cases where a newline may not terminate
    // an expression as expected when the following tokens are valid
    // continuations of those expressions
    // http://eslint.org/docs/rules/no-unexpected-multiline
    'no-unexpected-multiline': [ERROR],

    // 80 char line limit. The 4 means tabs == 4 chars
    'max-len': [ERROR, 80, 4],

    // Variables must be used but params don't need to be
    'no-unused-vars': [ERROR, {'vars': 'all', 'args': 'none'}],

    // Dangling commas required when the line doesn't end with ] or }
    'comma-dangle': [ERROR, 'only-multiline'],

    // Turn off rule to disable console statements.
    'no-console': [OFF],
  },
}