.eslintrc.js

const OFF = 0,
    WARN = 1,
    ERROR = 2;

module.exports = {
    env: {
        es6: true,
    },

    ecmaFeatures: {
        // env=es6 doesn't include modules, which we are using
        modules: true,
    },

    extends: ['eslint:recommended', 'plugin:@typescript-eslint/recommended'],
    parser: '@typescript-eslint/parser',
    plugins: ['@typescript-eslint'],
    root: true,

    rules: {
        // Possible Errors (overrides from recommended set)
        'no-extra-parens': WARN,
        'no-unexpected-multiline': ERROR,
        // All JSDoc comments must be valid
        'valid-jsdoc': [
            ERROR,
            {
                requireReturn: false,
                requireReturnDescription: false,
                requireParamDescription: true,
                prefer: {
                    return: 'returns',
                },
            },
        ],

        // Best Practices

        // Allowed a getter without setter, but all setters require getters
        'accessor-pairs': [
            ERROR,
            {
                getWithoutSet: false,
                setWithoutGet: true,
            },
        ],
        'block-scoped-var': WARN,
        'consistent-return': ERROR,
        curly: ERROR,
        'default-case': WARN,
        // the dot goes with the property when doing multiline
        'dot-location': [WARN, 'property'],
        'dot-notation': WARN,
        eqeqeq: [ERROR, 'smart'],
        'guard-for-in': WARN,
        'no-alert': ERROR,
        'no-caller': ERROR,
        'no-case-declarations': WARN,
        'no-div-regex': WARN,
        'no-else-return': WARN,
        'no-labels': WARN,
        'no-empty-pattern': WARN,
        'no-eq-null': WARN,
        'no-eval': ERROR,
        'no-extend-native': ERROR,
        'no-extra-bind': WARN,
        'no-floating-decimal': WARN,
        'no-implicit-coercion': [
            WARN,
            {
                boolean: true,
                number: true,
                string: true,
            },
        ],
        'no-implied-eval': ERROR,
        'no-invalid-this': ERROR,
        'no-iterator': ERROR,
        'no-labels': WARN,
        'no-lone-blocks': WARN,
        'no-loop-func': ERROR,
        'no-magic-numbers': WARN,
        'no-multi-spaces': ERROR,
        'no-multi-str': WARN,
        'no-native-reassign': ERROR,
        'no-new-func': ERROR,
        'no-new-wrappers': ERROR,
        'no-new': ERROR,
        'no-octal-escape': ERROR,
        'no-param-reassign': ERROR,
        'no-process-env': WARN,
        'no-proto': ERROR,
        'no-redeclare': ERROR,
        'no-return-assign': ERROR,
        'no-script-url': ERROR,
        'no-self-compare': ERROR,
        'no-throw-literal': ERROR,
        'no-unused-expressions': ERROR,
        'no-useless-call': ERROR,
        'no-useless-concat': ERROR,
        'no-void': WARN,
        // Produce warnings when something is commented as TODO or FIXME
        'no-warning-comments': [
            WARN,
            {
                terms: ['TODO', 'FIXME'],
                location: 'start',
            },
        ],
        'no-with': WARN,
        radix: WARN,
        'vars-on-top': ERROR,
        // Enforces the style of wrapped functions
        'wrap-iife': [ERROR, 'outside'],
        yoda: ERROR,

        // Strict Mode - for ES6, never use strict.
        strict: [ERROR, 'never'],

        // Variables
        'init-declarations': [ERROR, 'always'],
        'no-catch-shadow': WARN,
        'no-delete-var': ERROR,
        'no-label-var': ERROR,
        'no-shadow-restricted-names': ERROR,
        'no-shadow': WARN,
        // We require all vars to be initialized (see init-declarations)
        // If we NEED a var to be initialized to undefined, it needs to be explicit
        'no-undef-init': OFF,
        'no-undef': WARN,
        'no-undefined': OFF,
        'no-unused-vars': WARN,
        // Disallow hoisting - let & const don't allow hoisting anyhow
        'no-use-before-define': ERROR,

        // Node.js and CommonJS
        'callback-return': [WARN, ['callback', 'next']],
        'global-require': ERROR,
        'handle-callback-err': WARN,
        'no-mixed-requires': WARN,
        'no-new-require': ERROR,
        // Use path.concat instead
        'no-path-concat': ERROR,
        'no-process-exit': ERROR,
        'no-restricted-modules': OFF,
        'no-sync': WARN,

        // ECMAScript 6 support
        'arrow-body-style': OFF,
        'arrow-parens': [ERROR, 'always'],
        'arrow-spacing': [ERROR, { before: true, after: true }],
        'constructor-super': ERROR,
        'generator-star-spacing': [ERROR, 'before'],
        'no-confusing-arrow': ERROR,
        'no-class-assign': ERROR,
        'no-const-assign': ERROR,
        'no-dupe-class-members': ERROR,
        'no-this-before-super': ERROR,
        'no-var': WARN,
        'object-shorthand': [WARN, 'never'],
        'prefer-arrow-callback': WARN,
        'prefer-spread': WARN,
        'prefer-template': WARN,
        'require-yield': ERROR,

        // Stylistic - everything here is a warning because of style.
        'array-bracket-spacing': OFF,
        'block-spacing': [WARN, 'always'],
        'brace-style': [WARN, '1tbs', { allowSingleLine: false }],
        camelcase: WARN,
        'comma-spacing': [WARN, { before: false, after: true }],
        'comma-style': [WARN, 'last'],
        'computed-property-spacing': [WARN, 'never'],
        'consistent-this': [WARN, 'self'],
        'eol-last': WARN,
        'func-names': WARN,
        'func-style': [WARN, 'declaration'],
        'id-length': OFF,
        indent: [WARN, 4],
        'jsx-quotes': [WARN, 'prefer-double'],
        'linebreak-style': [WARN, 'unix'],
        'lines-around-comment': [WARN, { beforeBlockComment: true }],
        'max-depth': [WARN, 8],
        'max-len': OFF,
        'max-nested-callbacks': [WARN, 8],
        'max-params': [WARN, 8],
        'new-cap': WARN,
        'new-parens': WARN,
        'no-array-constructor': WARN,
        'no-bitwise': OFF,
        'no-continue': OFF,
        'no-inline-comments': OFF,
        'no-lonely-if': WARN,
        'no-mixed-spaces-and-tabs': WARN,
        'no-multiple-empty-lines': WARN,
        'no-negated-condition': OFF,
        'no-nested-ternary': WARN,
        'no-new-object': WARN,
        'no-plusplus': OFF,
        'no-spaced-func': WARN,
        'no-ternary': OFF,
        'no-trailing-spaces': WARN,
        'no-underscore-dangle': WARN,
        'no-unneeded-ternary': WARN,
        'no-async-promise-executor': OFF,
        'object-curly-spacing': [WARN, 'always'],
        'one-var': OFF,
        'operator-assignment': [WARN, 'never'],
        'operator-linebreak': [WARN, 'before'],
        'padded-blocks': [WARN, 'never'],
        'quote-props': [WARN, 'consistent-as-needed'],
        quotes: [WARN, 'single'],
        'require-jsdoc': [
            WARN,
            {
                require: {
                    FunctionDeclaration: true,
                    MethodDefinition: true,
                    ClassDeclaration: false,
                },
            },
        ],
        'semi-spacing': [WARN, { before: false, after: true }],
        semi: [ERROR, 'always'],
        'sort-vars': OFF,
        'keyword-spacing': ERROR,
        'space-before-blocks': [WARN, 'always'],
        'space-before-function-paren': [WARN, 'never'],
        'space-in-parens': [WARN, 'never'],
        'space-infix-ops': [WARN, { int32Hint: true }],
        'space-unary-ops': ERROR,
        'spaced-comment': [WARN, 'always'],
        'wrap-regex': WARN,
    },
};