.eslintrc.js

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

module.exports = {
	parserOptions: {
		ecmaVersion: 2018,
		sourceType: 'module',
	},

	env: {
		es6: true,
	},

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

	extends: 'eslint:recommended',

	globals: { console: true },

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

		// 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': OFF,
		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-empty-label': 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': OFF,
		'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': OFF,
		'no-process-env': WARN,
		'no-proto': ERROR,
		'no-redeclare': ERROR,
		'no-return-assign': OFF,
		'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': OFF,
		// 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': OFF,
		'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': ERROR,
		'no-undefined': OFF,
		'no-unused-vars': OFF,
		// Disallow hoisting - let & const don't allow hoisting anyhow
		'no-use-before-define': OFF,

		// Node.js and CommonJS
		'callback-return': OFF,
		'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': OFF,
		'arrow-spacing': [ERROR, { before: true, after: true }],
		'constructor-super': ERROR,
		'generator-star-spacing': [ERROR, 'before'],
		// 'no-arrow-condition': 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,
		'no-console': OFF,

		// Stylistic - everything here is a warning because of style.
		'array-bracket-spacing': [WARN, 'always'],
		'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': [WARN, { min: 2, max: 32 }],
		indent: [WARN, 'tab'],
		'jsx-quotes': [WARN, 'prefer-double'],
		'linebreak-style': [WARN, 'unix'],
		'lines-around-comment': [WARN, { beforeBlockComment: false }],
		'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,
		'object-curly-spacing': [WARN, 'always'],
		'one-var': OFF,
		'operator-assignment': [WARN, 'never'],
		'operator-linebreak': OFF,
		'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,
		// 'space-after-keywords': [WARN, 'always'],
		'space-before-blocks': [WARN, 'always'],
		'space-before-function-paren': [WARN, 'never'],
		// 'space-before-keywords': [WARN, 'always'],
		'space-in-parens': [WARN, 'never'],
		'space-infix-ops': [WARN, { int32Hint: true }],
		// 'space-return-throw-case': ERROR,
		'space-unary-ops': ERROR,
		'spaced-comment': [WARN, 'always'],
		'wrap-regex': WARN,
	},
};