_.eslintrc.js

/** JavaScript Versions
 *  5 is minimum -> Last IE11
 *  6 = 2015 -> Node >8.10, iOS12+
 *  7 = 2016 -> FF78+,
 *  8 = 2017 -> Node 10.9+
 *  9 = 2018 -> Node 12.11+
 * 10 = 2019 -> Node 12.20 LTS
 * 11 = 2020 -> Node 14 LTS
 * 12 = 2021 -> Node 16
 */
/** Node.js supports (https://node.green/):
 * v07 - async/await
 * v09 - tagged template literals with invalid escape sequences,  RegExp lookbehind assertions
 * v10 - optional catch binding (no need for err param on catch), BigInt, import.meta,
 *         RegExp Unicode property escape sequences \p{...},
 *         trimStart/trimEnd, async iteration, Promise.prototype.finally,
 *         RegExp named capture groups
 * v11 - Array.prototype.{flat,flatMap}, Symbol.prototype.description
 * v12 - Promise.allSettled, globalThis, numeric separators, Object.fromEntries
 * v13 - import (modules), dynamic import(), export
 * v14 - optional chaining, Nullish Coalescing operators, String.prototype.matchAll,
 *         Intl.DisplayNames, Intl.DateTimeFormat, (Experimental: Async Local Storage, Top-Level Await, Diagnostic report),
 *         WeakReferences, private class methods
 * v15 - logical assignment operators, String.prototype.replaceAll, Promise.any, AggregateError, AbortController,
 *        (Experimental Promisified setTimeout/setImmediate)
 * v16 - Promisified setTimeout/setImmediate, RegExp match indices. npm v7 (peer deps now installed again).
 *       fs.rmdir no longer supports recursive (use new fs.rm)
 * v17 - OpenSSL 3 (incl QUIC), Readline Promise API
 * v18 - (Experimental: Fetch API, Web Streams API, Test Runner), HTTP Timeouts, findLast/findLastIndex array methods,
 *       Improvements to the Intl.Locale API [calendars, collations, hourCycles, numberingSystems, timeZones, textInfo, weekInfo],
 *       Intl.supportedValuesOf function
 * v19 - (Experimental: node --watch), HTTP(S)/1.1 KeepAlive by default, Stable WebCrypto API, Intl.NumberFormat
 */

module.exports = {
    root: true,
    env: {
        browser: false,
        commonjs: true,
        es2022: true,
        jquery: false,
        node: true,
        'shared-node-browser': false,
    },
    globals: {
        Set: true, // Not sure why eslint doesn't recognise this as it is part of node.js since v0.12
        RED: true,
    },
    parserOptions: {
        // Only ESLint 6.2.0 and later support ES2020. Node.js v12+ supports some things only ratified in 2020
        // ecmaVersion: 2022,
        sourceType: 'script'
    },
    plugins: [
        'html',     // Check scripts in HTML. https://www.npmjs.com/package/eslint-plugin-html
        'es',       // Help avoid js that is too new. https://eslint-plugin-es.mysticatea.dev/
        'jsdoc',    // JSDoc. https://www.npmjs.com/package/eslint-plugin-jsdoc
        'promise',  // Better promises. https://www.npmjs.com/package/eslint-plugin-promise
        'sonarjs',  // Detect bugs and suspicious patterns. https://github.com/SonarSource/eslint-plugin-sonarjs
        // 'prettier', // https://www.npmjs.com/package/eslint-plugin-prettier
        // 'eslint-plugin-n', // loads itself from extends, no need to manually load
    ],
    extends: [
        'standard', // Also loads the n plugin
        // 'eslint:recommended',
        'plugin:es/no-new-in-esnext',
        'plugin:jsdoc/recommended',
        'plugin:promise/recommended',
        // 'plugin:sonarjs/recommended-legacy', // NB: Needs changing for eslint v9. https://www.npmjs.com/package/eslint-plugin-sonarjs#usage
        // 'plugin:prettier/recommended',
        // The n plugin reads the min. node.js version from package.json and error's any ES features not available in that version.
        'plugin:n/recommended',
    ],
    overrides: [
        { // Override for Node-RED Editor js & html files
            env: {
                browser: true,
                es2019: true,
                es2022: false,
                jquery: true,
                node: false,
            },
            files: [
                'resources/*.js',
                'nodes/**/*.html',
                'src/editor/**/*.{js,html}',
            ],
            parserOptions: {
                sourceType: 'script',
            },
            rules: {
                // remove once min engines moves to node.js v14+
                'es/no-optional-chaining': 'error',
                'es/no-dynamic-import': 'error',
                'es/no-nullish-coalescing-operators': 'error',
            }
        },
        { // Override for front-end & docs std js & html files
            env: {
                browser: true,
                es2019: true,
                es2022: false,
                jquery: false,
                node: false,
            },
            files: [
                'front-end/**/*.js',
                'front-end/**/*.html',
                'docs/**/*.js',
                'docs/**/*.html',
            ],
            excludedFiles: [
                '*.{esm.js,esm.min.js}',
            ],
            parserOptions: {
                sourceType: 'script',
            },
            rules: {
                // remove once min engines moves to node.js v14+
                'es/no-optional-chaining': 'error',
                'es/no-dynamic-import': 'error',
                'es/no-nullish-coalescing-operators': 'error',
            }
        },
        { // Override for front-end esm js & html files
            env: {
                browser: true,
                es2019: false,
                es2022: true,
                jquery: false,
                node: false,
            },
            files: [
                'front-end/**/*.esm.js',
                'front-end/**/*.esm.min.js',
            ],
            excludedFiles: [
                '*.{esm.js,esm.min.js}',
            ],
            parserOptions: {
                sourceType: 'module',
            },
            rules: {
                // remove once min engines moves to node.js v14+
                'es/no-optional-chaining': 'error',
                'es/no-dynamic-import': 'error',
                'es/no-nullish-coalescing-operators': 'error',
            }
        },
        { // Override for src esm js files
            env: {
                browser: true,
                es2019: false,
                es2022: true,
                jquery: false,
                node: false,
            },
            files: [
                'src/components/*.js',
                'src/front-end-module/*.js',
            ],
            parserOptions: {
                sourceType: 'module',
            },
        },
        { // Override for .eslintrc.js/cjs files
            env: {
                browser: false,
                commonjs: true,
                es2022: true,
                jquery: false,
                node: true,
            },
            files: [
                '.eslintrc.{js,cjs}',
            ],
            parserOptions: {
                sourceType: 'script',
            }
        },
        { // Override for ESM files
            files: ['*.module.js', '*.mod.js', '*.mjs'],
            parserOptions: {
                sourceType: 'module',
            },
        },
    ],
    rules: {
        'n/no-process-exit': 'error',

        // remove once min engines moves to node.js v14+
        // 'es/no-optional-chaining': 'error',
        // 'es/no-dynamic-import': 'error',
        // 'es/no-nullish-coalescing-operators': 'error',

        // remove once min engines moves to node.js v15+
        'es/no-logical-assignment-operators': 'error',
        'es/no-promise-any': 'error',
        'es/no-numeric-separators': 'error',

        // Tidy up some jsdoc oddities
        'jsdoc/multiline-blocks': 0,
        'jsdoc/newline-after-description': 0,
        'jsdoc/no-multi-asterisks': 0,
        'jsdoc/tag-lines': 0,
        'jsdoc/valid-types': 0, // Rubbish, fails on common type configs
        'jsdoc/no-undefined-types': 0, // ['error'|'warn', {'definedTypes':['Promise']}],

        // Try to keep code complexity in functions to a minimum
        'sonarjs/cognitive-complexity': ['error', 60],  // default is 15! Need to try and improve this :-)
        'sonarjs/no-duplicate-string': ['warn', { 'threshold': 5 }],  // default is 3
        'sonarjs/no-commented-code': 0,

        // Make Standard less annoying
        'brace-style': 'off',     // You should only use one-true-brace style but sometimes we want to compress things a bit.
        'comma-dangle': 'off',    // Lack of dangles wastes soo much time correcting lists
        'dot-notation': 'off',    // Turn off to allow for tslint's brain-dead treatment of expando objects in JS
        'indent': ['error', 4, { 'SwitchCase': 1 }],   // Standard wants 2, I like 4
        'space-before-function-paren': 'off', // No, don't need space between fn and arg!
        'no-multi-spaces': 'off', // Readability is more important than size (reduce size using uglify)
        'object-shorthand': ['error', 'consistent'],
        'padded-blocks': 'off',   // Sometimes you just need some space! See above.
        'space-in-parens': 'off', // Sometimes you just need some space!
        'spaced-comment': ['error', 'always', {
            'markers': ['html', '#region', '#endregion']
        }],
        'quote-props': 'off',     // Sometimes it is necessary and then much nicer to be able to quote things that don't need it.
    }
}