.eslintrc.js

module.exports = {
	parser: 'babel-eslint',
	extends: 'eslint:recommended',

	env: {
		node: true,
		es6: true
	},

	parserOptions: {
		ecmaVersion: 2017,
		ecmaFeatures: {
			arrowFunctions: true,
			binaryLiterals: true,
			blockBindings: true,
			classes: true,
			defaultParams: true,
			destructuring: true,
			forOf: true,
			generators: true,
			modules: true,
			objectLiteralComputedProperties: true,
			objectLiteralDuplicateProperties: true,
			objectLiteralShorthandMethods: true,
			objectLiteralShorthandProperties: true,
			octalLiterals: true,
			regexUFlag: true,
			regexYFlag: true,
			spread: true,
			superInFunctions: true,
			templateStrings: true,
			unicodeCodePointEscapes: true,
			globalReturn: true,
			jsx: true
		}
	},

	rules: {
		//
		//Possible Errors
		//
		// The following rules point out areas where you might have made mistakes.
		//
		'comma-dangle': 0, // disallow or enforce trailing commas
		'no-cond-assign': 2, // disallow assignment in conditional expressions
		'no-console': 0, // disallow use of console (off by default in the node environment)
		'no-constant-condition': 2, // disallow use of constant expressions in conditions
		'no-control-regex': 2, // disallow control characters in regular expressions
		'no-debugger': 2, // disallow use of debugger
		'no-dupe-args': 2, // disallow duplicate arguments in functions
		'no-dupe-keys': 2, // disallow duplicate keys when creating object literals
		'no-duplicate-case': 2, // disallow a duplicate case label.
		'no-empty': 2, // disallow empty statements

		'no-ex-assign': 2, // disallow assigning to the exception in a catch block
		'no-extra-boolean-cast': 2, // disallow double-negation boolean casts in a boolean context
		'no-extra-parens': 0, // disallow unnecessary parentheses (off by default)
		'no-extra-semi': 2, // disallow unnecessary semicolons
		'no-func-assign': 2, // disallow overwriting functions written as function declarations
		'no-inner-declarations': 2, // disallow function or variable declarations in nested blocks
		'no-invalid-regexp': 2, // disallow invalid regular expression strings in the RegExp constructor
		'no-irregular-whitespace': 2, // disallow irregular whitespace outside of strings and comments
		'no-negated-in-lhs': 2, // disallow negation of the left operand of an in expression
		'no-obj-calls': 2, // disallow the use of object properties of the global object (Math and JSON) as functions
		'no-regex-spaces': 2, // disallow multiple spaces in a regular expression literal
		'no-sparse-arrays': 2, // disallow sparse arrays
		'no-unreachable': 2, // disallow unreachable statements after a return, throw, continue, or break statement
		'use-isnan': 2, // disallow comparisons with the value NaN
		'valid-jsdoc': 1, // Ensure JSDoc comments are valid (off by default)
		'valid-typeof': 2, // Ensure that the results of typeof are compared against a valid string

		//
		// Best Practices
		//
		// These are rules designed to prevent you from making mistakes.
		// They either prescribe a better way of doing something or help you avoid footguns.
		//
		'block-scoped-var': 0, // treat var statements as if they were block scoped (off by default). 0: deep destructuring is not compatible https://github.com/eslint/eslint/issues/1863
		complexity: 0, // specify the maximum cyclomatic complexity allowed in a program (off by default)
		'consistent-return': 0, // require return statements to either always or never specify values
		curly: 2, // specify curly brace conventions for all control statements
		'default-case': 2, // require default case in switch statements (off by default)
		'dot-notation': 2, // encourages use of dot notation whenever possible
		eqeqeq: 2, // require the use of === and !==
		'guard-for-in': 2, // make sure for-in loops have an if statement (off by default)
		'no-alert': 0, // disallow the use of alert, confirm, and prompt
		'no-caller': 2, // disallow use of arguments.caller or arguments.callee
		'no-div-regex': 2, // disallow division operators explicitly at beginning of regular expression (off by default)
		'no-else-return': 0, // disallow else after a return in an if (off by default)
		'no-eq-null': 2, // disallow comparisons to null without a type-checking operator (off by default)
		'no-eval': 2, // disallow use of eval()
		'no-extend-native': 2, // disallow adding to native types
		'no-extra-bind': 2, // disallow unnecessary function binding
		'no-fallthrough': 2, // disallow fallthrough of case statements
		'no-floating-decimal': 2, // disallow the use of leading or trailing decimal points in numeric literals (off by default)
		'no-implied-eval': 2, // disallow use of eval()-like methods
		'no-iterator': 2, // disallow usage of __iterator__ property
		'no-labels': 2, // disallow use of labeled statements
		'no-lone-blocks': 2, // disallow unnecessary nested blocks
		'no-loop-func': 2, // disallow creation of functions within loops
		'no-multi-spaces': 2, // disallow use of multiple spaces
		'no-multi-str': 2, // disallow use of multiline strings
		'no-native-reassign': 2, // disallow reassignments of native objects
		'no-new': 2, // disallow use of new operator when not part of the assignment or comparison
		'no-new-func': 2, // disallow use of new operator for Function object
		'no-new-wrappers': 2, // disallows creating new instances of String,Number, and Boolean
		'no-octal': 2, // disallow use of octal literals
		'no-octal-escape': 2, // disallow use of octal escape sequences in string literals, such as var foo = "Copyright \251";
		'no-param-reassign': 0, // disallow reassignment of function parameters (off by default)
		'no-process-env': 0, // disallow use of process.env (off by default)
		'no-proto': 2, // disallow usage of __proto__ property
		'no-redeclare': 2, // disallow declaring the same variable more then once
		'no-return-assign': 2, // disallow use of assignment in return statement
		'no-script-url': 2, // disallow use of javascript: urls.
		'no-self-compare': 2, // disallow comparisons where both sides are exactly the same (off by default)
		'no-sequences': 2, // disallow use of comma operator
		'no-throw-literal': 2, // restrict what can be thrown as an exception (off by default)
		'no-unused-expressions': 2, // disallow usage of expressions in statement position
		'no-void': 2, // disallow use of void operator (off by default)
		'no-warning-comments': [
			0,
			{
				terms: ['todo', 'fixme'],
				location: 'start'
			}
		], // disallow usage of configurable warning terms in comments": 2, // e.g. TODO or FIXME (off by default)
		'no-with': 2, // disallow use of the with statement
		radix: 2, // require use of the second argument for parseInt() (off by default)
		'vars-on-top': 0, // requires to declare all vars on top of their containing scope (off by default)
		'wrap-iife': 2, // require immediate function invocation to be wrapped in parentheses (off by default)
		yoda: 2, // require or disallow Yoda conditions

		//
		// Strict Mode
		//
		// These rules relate to using strict mode.
		//
		strict: 0, // controls location of Use Strict Directives. 0: required by `babel-eslint`

		//
		// Variables
		//
		// These rules have to do with variable declarations.
		//
		'no-catch-shadow': 2, // disallow the catch clause parameter name being the same as a variable in the outer scope (off by default in the node environment)
		'no-delete-var': 2, // disallow deletion of variables
		'no-label-var': 2, // disallow labels that share a name with a variable
		'no-shadow': 2, // disallow declaration of variables already declared in the outer scope
		'no-shadow-restricted-names': 2, // disallow shadowing of names such as arguments
		'no-undef': 2, // disallow use of undeclared variables unless mentioned in a /*global */ block
		'no-undef-init': 2, // disallow use of undefined when initializing variables
		'no-undefined': 0, // disallow use of undefined variable (off by default)
		'no-unused-vars': 0, // disallow declaration of variables that are not used in the code
		'no-use-before-define': 2, // disallow use of variables before they are defined

		//
		//Stylistic Issues
		//
		// These rules are purely matters of style and are quite subjective.
		//
		indent: [0, 'tab'], // this option sets a specific tab width for your code (off by default)
		'brace-style': 1, // enforce one true brace style (off by default)
		camelcase: 0, // require camel case names
		'comma-spacing': [
			1,
			{
				before: false,
				after: true
			}
		], // enforce spacing before and after comma
		'comma-style': [1, 'last'], // enforce one true comma style (off by default)
		'consistent-this': [1, '_this'], // enforces consistent naming when capturing the current execution context (off by default)
		'eol-last': 1, // enforce newline at the end of file, with no multiple empty lines
		'func-names': 0, // require function expressions to have a name (off by default)
		'func-style': 0, // enforces use of function declarations or expressions (off by default)
		'key-spacing': [
			1,
			{
				beforeColon: false,
				afterColon: true
			}
		], // enforces spacing between keys and values in object literal properties
		'max-nested-callbacks': [1, 4], // specify the maximum depth callbacks can be nested (off by default)
		'new-cap': [
			1,
			{
				newIsCap: true,
				capIsNew: false
			}
		], // require a capital letter for constructors
		'new-parens': 1, // disallow the omission of parentheses when invoking a constructor with no arguments
		'newline-after-var': 0, // allow/disallow an empty newline after var statement (off by default)
		'no-array-constructor': 1, // disallow use of the Array constructor
		'no-inline-comments': 0, // disallow comments inline after code (off by default)
		'no-lonely-if': 1, // disallow if as the only statement in an else block (off by default)
		'no-mixed-spaces-and-tabs': 1, // disallow mixed spaces and tabs for indentation
		'no-multiple-empty-lines': [
			1,
			{
				max: 2
			}
		], // disallow multiple empty lines (off by default)
		'no-nested-ternary': 1, // disallow nested ternary expressions (off by default)
		'no-new-object': 1, // disallow use of the Object constructor
		'no-spaced-func': 1, // disallow space between function identifier and application
		'no-ternary': 0, // disallow the use of ternary operators (off by default)
		'no-trailing-spaces': 1, // disallow trailing whitespace at the end of lines
		'no-underscore-dangle': 0, // disallow dangling underscores in identifiers
		//"one-var": ["warn", { "initialized": "never" }], // allow just one var statement per function (off by default)
		'operator-assignment': [0, 'never'], // require assignment operator shorthand where possible or prohibit it entirely (off by default)
		'padded-blocks': [0, 'always'], // enforce padding within blocks (off by default)
		'quote-props': [0, 'as-needed'], // require quotes around object literal property names (off by default)
		quotes: [0, 'single'], // specify whether double or single quotes should be used
		semi: [1, 'always'], // require or disallow use of semicolons instead of ASI
		'semi-spacing': [
			1,
			{
				before: false,
				after: true
			}
		], // enforce spacing before and after semicolons
		'sort-vars': 0, // sort variables within the same declaration block (off by default)

		'space-before-blocks': [1, 'always'], // require or disallow space before blocks (off by default)
		'space-before-function-paren': [
			0,
			{
				anonymous: 'always',
				named: 'never'
			}
		], // require or disallow space before function opening parenthesis (off by default)

		//"space-infix-ops": [1], // require spaces around operators
		//"space-return-throw-case": [1, "always"], // require a space after return, throw, and case
		'space-unary-ops': [
			1,
			{
				words: true,
				nonwords: false
			}
		], // Require or disallow spaces before/after unary operators (words on by default, nonwords off by default)
		'wrap-regex': 0, // require regex literals to be wrapped in parentheses (off by default)

		//
		// ECMAScript 6
		//
		// These rules are only relevant to ES6 environments and are off by default.
		//
		'no-var': 0, // require let or const instead of var (off by default)
		'generator-star-spacing': [2, 'before'], // enforce the spacing around the * in generator functions (off by default)

		//
		// Legacy
		//
		// The following rules are included for compatibility with JSHint and JSLint.
		// While the names of the rules may not match up with the JSHint/JSLint counterpart,
		// the functionality is the same.
		//
		'max-depth': [2, 3], // specify the maximum depth that blocks can be nested (off by default)
		'max-len': [1, 150, 2], // specify the maximum length of a line in your program (off by default)
		'max-params': [1, 10], // limits the number of parameters that can be used in the function declaration. (off by default)
		'max-statements': 0, // specify the maximum number of statement allowed in a function (off by default)
		'no-bitwise': 1, // disallow use of bitwise operators (off by default)
		'no-plusplus': 0 // disallow use of unary operators, ++ and -- (off by default)
	}
};