.eslintrc.js

module.exports = {
  "root": true,
  "extends": "eslint:recommended",
  "env": {
    "node": true,
    "es6": true,
    "mocha": true
  },
  "parserOptions": {
    "ecmaVersion": 2018,
    "sourceType": "script"
  },

  // 0 - off
  // 1 - warn
  // 2 - error (exit code 1)
  "rules": {
    // Possible Errors
    // http://eslint.org/docs/rules/#possible-errors
    "comma-dangle": ["error", "only-multiline"],
    "no-control-regex": "error",
    "no-debugger": 2,
    "no-console": 2,
    "no-dupe-args": 2,
    "no-dupe-keys": 2,
    "no-duplicate-case": 2,
    "no-empty-character-class": 2,
    "no-ex-assign": 2,
    "no-extra-boolean-cast": 2,
    "no-extra-parens": [2, "functions"],
    "no-extra-semi": 2,
    "no-func-assign": 2,
    "no-invalid-regexp": 2,
    "no-irregular-whitespace": 2,
    "no-negated-in-lhs": 2,
    "no-obj-calls": 2,
    "no-proto": 2,
    "no-unexpected-multiline": 2,
    "no-unreachable": 2,
    "use-isnan": 2,
    "valid-typeof": 2,
    "no-var": 2,
    "object-curly-spacing": [2, "never"],
    "no-constant-condition": [2, { "checkLoops": false }],

    // Best Practices
    // http://eslint.org/docs/rules/#best-practices
    "no-fallthrough": 2,
    "no-octal": 2,
    "no-redeclare": 2,
    "no-self-assign": 2,
    "no-unused-labels": 2,
    "no-useless-catch": 2,

    // Strict Mode
    // http://eslint.org/docs/rules/#strict-mode
    "strict": [2, "global"],

    // Variables
    // http://eslint.org/docs/rules/#variables
    "no-delete-var": 2,
    "no-undef": 2,
    //"no-unused-vars": [2, {"args": "after-used"}],
    // don't complain about unused args
    "no-unused-vars": [2, {"args": "none"}],

    // Node.js and CommonJS
    // http://eslint.org/docs/rules/#nodejs-and-commonjs
    "no-mixed-requires": 2,
    "no-new-require": 2,
    "no-path-concat": 2,
    "no-restricted-modules": [2, "sys", "_linklist"],

    // Stylistic Issues
    // http://eslint.org/docs/rules/#stylistic-issues
    "comma-spacing": 2,
    "eol-last": 2,
    "indent": [2, 2, {"SwitchCase": 1}],
    "keyword-spacing": 2,
    "max-len": [2, 130, 2, {
      "ignoreComments": true,
      "ignoreStrings": true,
      "ignoreTemplateLiterals": true,
      "ignoreRegExpLiterals": true
      }],
    "new-parens": 2,
    "no-mixed-spaces-and-tabs": 2,
    "no-multiple-empty-lines": [2, {"max": 2}],
    "no-trailing-spaces": 2,
    "quotes": [2, "single", {"avoidEscape": true}],
    // semi: 2
    "space-before-blocks": [2, "always"],
    "space-before-function-paren": [2, "never"],
    // space-in-parens: [2, "never"]
    "space-infix-ops": ["warn", {"int32Hint": true}],
    "space-unary-ops": 2,
    "semi": ["warn", "always", {"omitLastInOneLineBlock": true}],

    // ECMAScript 6
    // http://eslint.org/docs/rules/#ecmascript-6
    // arrow-parens: [2, "always"]
    "arrow-spacing": [2, {"before": true, "after": true}],
    "constructor-super": 2,
    "no-class-assign": 2,
    // no-confusing-arrow: [2, {"allowParens": true}]
    "no-const-assign": 2,
    "no-dupe-class-members": 2,
    "no-new-symbol": 2,
    "no-this-before-super": 2,
    "prefer-const": 2
  }
}