.eslintrc

{
    "parserOptions": {
        "ecmaVersion": 2017,
        "sourceType": "module",

        // http://eslint.org/docs/user-guide/configuring#specifying-parser-options
        "ecmaFeatures": {
            "impliedStrict": true,
            "globalReturn": false,
            "jsx": false
        }
    },

    // http://eslint.org/docs/user-guide/configuring#specifying-environments
    "env": {
        "es6": true,
        "node": true,
        "mocha": true
    },

    // http://eslint.org/docs/user-guide/configuring#specifying-globals
    "globals": {},

    // http://eslint.org/docs/user-guide/configuring#configuring-plugins
    "plugins": [],


    "rules": {

        // http://eslint.org/docs/rules/#possible-errors
        "comma-dangle": [ 0, "never" ],
        "for-direction": 0,
        "getter-return": 2,
        "no-await-in-loop": 0,
        "no-compare-neg-zero": 2,
        "no-cond-assign": [ 2, "except-parens" ],
        "no-console": 1,
        "no-constant-condition": 0,
        "no-control-regex": 0,
        "no-debugger": 1,
        "no-dupe-args": 2,
        "no-dupe-keys": 2,
        "no-duplicate-case": 2,
        "no-empty": 1,
        "no-empty-character-class": 2,
        "no-ex-assign": 2,
        "no-extra-boolean-cast": 0,
        "no-extra-parens": 0,
        "no-extra-semi": 2,
        "no-func-assign": 0,
        "no-inner-declarations": [ 2, "both" ],
        "no-invalid-regexp": 2,
        "no-irregular-whitespace": 1,
        "no-multi-assign": 0,
        "no-obj-calls": 2,
        "no-prototype-builtins": 2,
        "no-regex-spaces": 0,
        "no-sparse-arrays": 1,
        "no-template-curly-in-string": 0,
        "no-unexpected-multiline": 1,
        "no-unreachable": 1,
        "no-unsafe-finally": 1,
        "no-unsafe-negation": 2,
        "no-whitespace-before-property)": 0,
        "use-isnan": 2,
        "valid-jsdoc": 0,
        "valid-typeof": 2,


        // http://eslint.org/docs/rules/#best-practices
        "accessor-pairs": 0,
        "array-callback-return": 2,
        "block-scoped-var": 2,
        "class-methods-use-this": 0,
        "complexity": [ 1, 20 ],
        "consistent-return": 2,
        "curly": [ 2, "all" ],
        "default-case": 2,
        "dot-location": [ 2, "property" ],
        "dot-notation": [ 2, {
            "allowKeywords": true
        } ],
        "eqeqeq": 2,
        "guard-for-in": 1,
        "no-alert": 2,
        "no-caller": 2,
        "no-case-declarations": 2,
        "no-div-regex": 2,
        "no-else-return": 1,
        "no-empty-function": 1,
        "no-empty-pattern": 2,
        "no-eq-null": 2,
        "no-eval": 2,
        "no-extend-native": [ 2, {
            "exceptions": []
        } ],
        "no-extra-bind": 2,
        "no-extra-label": 2,
        "no-fallthrough": 1,
        "no-floating-decimal": 2,
        "no-implicit-coercion": [ 2, {
            "boolean": false,
            "number": true,
            "string": true
        } ],
        "no-implied-eval": 2,
        "no-implicit-globals": 0,
        "no-invalid-this": 1,
        "no-iterator": 2,
        "no-labels": 2,
        "no-lone-blocks": 1,
        "no-loop-func": 2,
        "no-magic-numbers": 0,
        "no-multi-spaces": 0,
        "no-multi-str": 1,
        "no-new-func": 2,
        "no-new-wrappers": 1,
        "no-new": 2,
        "no-octal-escape": 2,
        "no-octal": 2,
        "no-param-reassign": 1,
        "no-process-env": 0,
        "no-proto": 2,
        "no-redeclare": 2,
        "no-restricted-properties": [ 0 ],
        "no-return-assign": [ 2, "except-parens" ],
        "no-return-await": 0,
        "no-script-url": 2,
        "no-self-assign": 2,
        "no-self-compare": 2,
        "no-sequences": 2,
        "no-throw-literal": 2,
        "no-unmodified-loop-condition": 1,
        "no-unused-expressions": [ 2, {
            "allowShortCircuit": true,
            "allowTernary": true
        } ],
        "no-unused-labels": 2,
        "no-useless-call": 1,
        "no-useless-concat": 2,
        "no-useless-escape": 2,
        "no-useless-return": 0, // conflicts with "callback-return"
        "no-void": 2,
        "no-warning-comments": [ 0, {
            "terms": [
                "todo",
                "fixme",
                "note"
            ],
            "location": "start"
        } ],
        "no-with": 2,
        "radix": 2,
        "vars-on-top": 0,
        "wrap-iife": [ 2, "inside" ],
        "yoda": [ 0, "never" ],


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


        // http://eslint.org/docs/rules/#variables
        "init-declarations": [ 0, "never", {
            "ignoreForLoopInit": true
        } ],
        "no-catch-shadow": 2,
        "no-delete-var": 2,
        "no-global-assign": 2,
        "no-label-var": 2,
        "no-restricted-globals": [ 0 ],
        "no-shadow": 2,
        "no-shadow-restricted-names": 2,
        "no-undef": 2,
        "no-undef-init": 0,
        "no-undefined": 0,
        "no-unused-vars": [ 2, {
            "vars": "all",
            "args": "after-used"
        } ],
        "no-use-before-define": 2,


        // http://eslint.org/docs/rules/#nodejs-and-commonjs
        "callback-return": [ 1, [
            "cb",
            "callback",
            "next"
        ] ],
        "global-require": 1,
        "handle-callback-err": [ 1, "^(e|err|error)$" ],
        "no-buffer-constructor": 2,
        "no-mixed-requires": [ 2, {
            "grouping": true
        } ],
        "no-new-require": 1,
        "no-path-concat": 1,
        "no-process-exit": 0,
        "no-restricted-imports": 0,
        "no-restricted-modules": 0,
        "no-sync": 1,


        // http://eslint.org/docs/rules/#stylistic-issues
        //   we could address many of the stylistic concerns with JSCS
        //   and we can gradually move from 1 (Warning) to 0 or 2
        "array-bracket-newline": [ 0, "consistent" ],
        "array-bracket-spacing": [ 0, "never" ],
        "array-element-newline": 0,
        "arrow-body-style": 0,
        "arrow-parens": [ 1, "always" ],
        "block-spacing": 0,
        "brace-style": 0,
        "camelcase": [ 2, {
            "properties": "never"
        } ],
        "capitalized-comments": [ 0, "always" ],
        "comma-spacing": 0,
        "comma-style": [ 1, "last" ],
        "computed-property-spacing": 0,
        "consistent-this": 0,
        "eol-last": 2,
        "func-call-spacing": 0,
        "func-name-matching": 2,
        "func-names": 0,
        "func-style": [ 1, "declaration", {
            "allowArrowFunctions": true
        } ],
        "function-paren-newline": [ 0, "consistent" ],
        "id-blacklist": 0,
        "id-length": [ 1, {
            "min": 1,
            "max": 40,
            "properties": "never",
            "exceptions": []
        } ],
        "id-match": 0,
        "implicit-arrow-linebreak": [ 0, "beside" ],
        "indent": [ 1, 2, {
            "SwitchCase": 1,
            "VariableDeclarator": 1,
            "outerIIFEBody": 1,
            "MemberExpression": 0,
            "FunctionDeclaration": {
                "parameters": 1,
                "body": 1
            },
            "FunctionExpression": {
                "parameters": 1,
                "body": 1
            },
            "CallExpression": {
                "arguments": 1
            },
            "ArrayExpression": 1,
            "ObjectExpression": 1,
            "ImportDeclaration": 1,
            "flatTernaryExpressions": false,
            "ignoredNodes": [],
            "ignoreComments": false
        } ],
        "jsx-quotes": 0,
        "key-spacing": 0,
        "keyword-spacing": 0,
        "line-comment-position": 0,
        "linebreak-style": [ 2, "unix" ],
        "lines-around-comment": 0,
        "lines-around-directive": 0,
        "lines-between-class-members": [ 0, "always" ],
        "max-depth": [ 1, 3 ],
        "max-len": [ 2, 120 ],
        "max-lines": 0,
        "max-nested-callbacks": [ 1, 4 ],
        "max-params": [ 1, 4 ],
        "max-statements": 0,
        "max-statements-per-line": [ 1, { "max": 2 } ],
        "multiline-comment-style": [ 0, "starred-block" ],
        "new-cap": 2,
        "new-parens": 2,
        "newline-after-var": 0,
        "newline-before-return": 0,
        "newline-per-chained-call": [ 0, {
            "ignoreChainWithDepth": 3
        } ],
        "no-array-constructor": 2,
        "no-bitwise": 0,
        "no-continue": 0,
        "no-inline-comments": 0,
        "no-lonely-if": 2,
        "no-mixed-operators": 1,
        "no-mixed-spaces-and-tabs": 2,
        "no-multiple-empty-lines": 0,
        "no-negated-condition": 1,
        "no-nested-ternary": 2,
        "no-new-object": 2,
        "no-plusplus": 0,
        "no-restricted-syntax": 0,
        "no-tabs": 1,
        "no-ternary": 0,
        "no-trailing-spaces": 2,
        "no-underscore-dangle": [ 0, {
            "allow": []
        } ],
        "no-unneeded-ternary": 2,
        "no-whitespace-before-property": 0,
        "nonblock-statement-body-position": [ 0, "any" ],
        "object-curly-newline": [ 0, "always" ],
        "object-curly-spacing": 0,
        "object-property-newline": 0,
        "one-var": [ 0, "never" ],
        "one-var-declaration-per-line": [ 2, "always" ],
        "operator-assignment": 0,
        "operator-linebreak": 0,
        "padded-blocks": 0,
        "padding-line-between-statements": [ 0 ],
        "quote-props": [ 2, "as-needed", {
            "keywords": false,
            "unnecessary": false,
            "numbers": true
        } ],
        "quotes": [ 2, "single", "avoid-escape" ],
        "require-jsdoc": 0,
        "semi-spacing": 0,
        "semi-style": [ 0, "last" ],
        "semi": [ 2, "always" ],
        "sort-imports": 0,
        "sort-keys": 0,
        "sort-vars": 0,
        "space-before-blocks": 0,
        "space-before-function-paren": 0,
        "space-in-parens": 0,
        "space-infix-ops": 0,
        "space-unary-ops": 0,
        "spaced-comment": 0,
        "switch-colon-spacing": [ 2, {
            "after": true,
            "before": false
        } ],
        "template-tag-spacing": [ 2, "always" ],
        "unicode-bom": [ 1, "never" ],
        "wrap-regex": 1,


        // http://eslint.org/docs/rules/#ecmascript-6
        "arrow-spacing": 0,
        "constructor-super": 2,
        "generator-star-spacing": 0,
        "no-class-assign": 2,
        "no-confusing-arrow": 2,
        "no-const-assign": 2,
        "no-dupe-class-members": 2,
        "no-duplicate-imports": 2,
        "no-new-symbol": 0,
        "no-this-before-super": 1,
        "no-useless-computed-key": 2,
        "no-useless-constructor": 1,
        "no-useless-rename": 2,
        "no-var": 2,
        "object-shorthand": [ 1, "always" ],
        "prefer-arrow-callback": 1,
        "prefer-const": 1,
        "prefer-destructuring": [ 0, {
          "array": true,
          "object": true
        } ],
        "prefer-numeric-literals": 2,
        "prefer-promise-reject-errors": 2,
        "prefer-rest-params": 1,
        "prefer-spread": 1,
        "prefer-template": 0,
        "require-await": 2,
        "require-yield": 2,
        "rest-spread-spacing": [ 0, "never" ],
        "symbol-description": 2,
        "template-curly-spacing": 0,
        "yield-star-spacing": 0
    }
}