.eslintrc.js

'use strict';

var OFF = 0;
var ERROR = 2;

var config = {
    extends: [],
    plugins: ['jsdoc'],
    env: {
        browser: false,
        node: true,
        es6: true
    },
    parserOptions: {
        ecmaVersion: 2018
    },
    rules: {}
};

if (!process.env.NO_LINT) {
    // possible errors
    config.rules['no-cond-assign'] = ERROR;
    config.rules['no-console'] = OFF;
    config.rules['no-constant-condition'] = ERROR;
    config.rules['no-control-regex'] = ERROR;
    config.rules['no-debugger'] = ERROR;
    config.rules['no-dupe-args'] = ERROR;
    config.rules['no-dupe-keys'] = ERROR;
    config.rules['no-duplicate-case'] = ERROR;
    config.rules['no-empty'] = ERROR;
    config.rules['no-empty-character-class'] = ERROR;
    config.rules['no-ex-assign'] = ERROR;
    config.rules['no-extra-boolean-cast'] = ERROR;
    config.rules['no-extra-semi'] = ERROR;
    config.rules['no-func-assign'] = ERROR;
    // config.rules['one-var'] = [ERROR, 'always']; // TODO: var overlapping
    // this is for variable hoisting, not necessary if we use block scoped declarations
    // config.rules['no-inner-declarations'] = [ ERROR, 'both' ];
    config.rules['no-invalid-regexp'] = ERROR;
    config.rules['no-irregular-whitespace'] = ERROR;
    config.rules['no-negated-in-lhs'] = ERROR;
    config.rules['no-reserved-keys'] = OFF;
    config.rules['no-regex-spaces'] = ERROR;
    config.rules['no-sparse-arrays'] = ERROR;
    config.rules['no-unreachable'] = ERROR;
    config.rules['use-isnan'] = ERROR;
    config.rules['valid-jsdoc'] = [
        ERROR,
        {
            requireReturnDescription: false,
            prefer: {
                return: 'returns'
            }
        }
    ];
    config.rules['valid-typeof'] = ERROR;

    // best practices
    config.rules['func-names'] = ERROR;
    config.rules['block-scoped-var'] = ERROR;
    config.rules['consistent-return'] = ERROR;
    config.rules['curly'] = OFF;
    config.rules['default-case'] = ERROR;
    config.rules['dot-notation'] = [ERROR, { allowKeywords: true }];
    config.rules['eqeqeq'] = ERROR;
    config.rules['guard-for-in'] = ERROR;
    config.rules['no-alert'] = ERROR;
    config.rules['no-caller'] = ERROR;
    config.rules['no-div-regex'] = ERROR;
    config.rules['no-eq-null'] = ERROR;
    config.rules['no-eval'] = ERROR;
    config.rules['no-extend-native'] = ERROR;
    config.rules['no-extra-bind'] = ERROR;
    config.rules['no-fallthrough'] = ERROR;
    config.rules['no-floating-decimal'] = ERROR;
    config.rules['no-implied-eval'] = ERROR;
    config.rules['no-iterator'] = ERROR;
    config.rules['no-labels'] = ERROR;
    config.rules['no-lone-blocks'] = ERROR;
    config.rules['no-loop-func'] = OFF;
    config.rules['no-multi-spaces'] = OFF;
    config.rules['no-multi-str'] = OFF;
    config.rules['no-native-reassign'] = ERROR;
    config.rules['no-new'] = OFF;
    config.rules['no-new-func'] = ERROR;
    config.rules['no-new-wrappers'] = ERROR;
    config.rules['no-octal'] = ERROR;
    config.rules['no-octal-escape'] = ERROR;
    config.rules['no-param-reassign'] = OFF;
    config.rules['no-proto'] = ERROR;
    config.rules['no-process-env'] = OFF;
    config.rules['no-redeclare'] = ERROR;
    config.rules['no-return-assign'] = ERROR;
    config.rules['no-script-url'] = ERROR;
    config.rules['no-self-compare'] = ERROR;
    config.rules['no-sequences'] = ERROR;
    config.rules['no-throw-literal'] = ERROR;
    config.rules['no-unused-expressions'] = ERROR;

    config.rules['no-warning-comments'] = [1];
    config.rules['no-with'] = ERROR;
    config.rules['radix'] = ERROR;
    config.rules['wrap-iife'] = ERROR;

    // strict mode
    config.rules['strict'] = [ERROR, 'global'];

    // variables
    config.rules['no-catch-shadow'] = ERROR;
    config.rules['no-delete-var'] = ERROR;
    config.rules['no-shadow'] = ERROR;
    config.rules['no-shadow-restricted-names'] = ERROR;
    config.rules['no-undef'] = ERROR;
    config.rules['no-undef-init'] = ERROR;
    config.rules['no-undefined'] = OFF;
    config.rules['no-unused-vars'] = [ERROR, { vars: 'all', args: 'none' }];
    config.rules['no-use-before-define'] = [ERROR, 'nofunc'];

    // node.js
    config.rules['handle-callback-err'] = [ERROR, '^.*(e|E)rr'];
    config.rules['no-mixed-requires'] = ERROR;
    config.rules['no-new-require'] = ERROR;
    config.rules['no-path-concat'] = OFF;
    config.rules['no-process-exit'] = OFF;
}

// stylistic.
if (!process.env.NO_STYLE) {
    // Global
    config.rules['max-len'] = [ERROR, { code: 80, ignoreComments: true }];

    // Prettier
    config.extends.push('prettier');
    config.plugins.push('prettier');
    config.rules['prettier/prettier'] = ERROR;

    // JSDoc
    config.rules['jsdoc/check-param-names'] = ERROR;
    config.rules['jsdoc/check-tag-names'] = ERROR;
    config.rules['jsdoc/newline-after-description'] = ERROR;
    config.rules['jsdoc/require-hyphen-before-param-description'] = ERROR;
    config.rules['jsdoc/require-param'] = ERROR;
    config.rules['jsdoc/require-param-description'] = ERROR;
    config.rules['jsdoc/require-param-type'] = ERROR;
    config.rules['jsdoc/require-returns-description'] = ERROR;
    config.rules['jsdoc/require-returns-type'] = ERROR;
}

module.exports = config;