.eslintrc.js

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

    globals: {
        describe: false,
        it: false,
        define: false,
    },

    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-empty-character-class': 2, // disallow the use of empty character classes in regular expressions
        '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
        'quote-props': 0, // disallow reserved words being used as object literal keys (off by default)
        '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': 2, // 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': 2, // 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': 0, // 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': 2, // 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': 0, // 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': 2, // 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': 0, // disallow usage of expressions in statement position
        'no-void': 2, // disallow use of void operator (off by default)
        'no-warning-comments': [1, { 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': ['error', 'inside'], // 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-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': 2, // 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": [1, 2], // 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": 1, // 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, 3], // 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": 1, // 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": 1, // disallow dangling underscores in identifiers
    "no-wrap-func": 1, // disallow wrapping of non-IIFE statements in parens
    "one-var": [1, "never"], // allow just one var statement per function (off by default)
    "operator-assignment": [1, "never"], // require assignment operator shorthand where possible or prohibit it entirely (off by default)
    "padded-blocks": [1, "never"], // enforce padding within blocks (off by default)
    "quote-props": [1, "as-needed"], // require quotes around object literal property names (off by default)
    "quotes": [1, "single"], // specify whether double or single quotes should be used
    "semi": [2, "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-after-keywords": [1, "always"], // require a space after certain keywords (off by default)
    "space-before-blocks": [1, "always"], // require or disallow space before blocks (off by default)
    "space-before-function-paren": [1, {"anonymous": "always", "named": "never"}], // require or disallow space before function opening parenthesis (off by default)
    "space-in-brackets": [1, "never"], // require or disallow spaces inside brackets (off by default)
    "space-in-parens": [1, "never"], // require or disallow spaces inside parentheses (off by default)
    "space-infix-ops": [1, "always"], // 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)
    "spaced-line-comment": [1, "always"], // require or disallow a space immediately following the // in a line comment (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': [0, 3], // specify the maximum depth that blocks can be nested (off by default)
        'max-len': [1, 120, 4], // specify the maximum length of a line in your program (off by default)
        'max-params': [0, 5], // 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': 0, // disallow use of bitwise operators (off by default)
        'no-plusplus': 0, // disallow use of unary operators, ++ and -- (off by default)
    },
};