best-practices.js

module.exports = {
  rules: {
    /**
     * Enforce getter and setter pairs in objects.
     *
     * https://eslint.org/docs/rules/accessor-pairs
     */
    "accessor-pairs": ["off", {
      "setWithoutGet": true,
      "getWithoutSet": true,
    }],

    /**
     * Enforce return statements in callbacks of array methods.
     *
     * https://eslint.org/docs/rules/array-callback-return
     */
    "array-callback-return": ["error", {
      "allowImplicit": true,
    }],

    /**
     * Enforce the use of variables within the scope they are defined.
     *
     * https://eslint.org/docs/rules/block-scoped-var
     */
    "block-scoped-var": "error",

    /**
     * Enforce that class methods utilize this.
     *
     * https://eslint.org/docs/rules/class-methods-use-this
     */
    "class-methods-use-this": ["error", {
      "exceptMethods": [],
    }],

    /**
     * Enforce a maximum cyclomatic complexity allowed in a program.
     *
     * https://eslint.org/docs/rules/complexity
     */
    "complexity": ["error", {
      "max": 30,
    }],

    /**
     * Require return statements to either always or never specify values.
     *
     * NOTES:
     * - Since reducer functions only return for matching cases, we dont supply
     *   a return value at the end of them. As a result, turn this rule off to
     *   avoid throwng this error.
     *
     * https://eslint.org/docs/rules/consistent-return
     */
    "consistent-return": ["off", {
      "treatUndefinedAsUnspecified": false,
    }],
   
    /**
     * Enforce consistent brace style for all control statements. 
     *
     * (fixable)
     *
     * https://eslint.org/docs/rules/curly
     */
    "curly": ["error", "all"],

    /**
     * Require default cases in switch statements.
     *
     * https://eslint.org/docs/rules/default-case
     */
    "default-case": ["error", {
      "commentPattern": "^no\\sdefault$",
    }],

    /**
     * Enforce consistent newlines before and after dots. 
     *
     * (fixable)
     *
     * https://eslint.org/docs/rules/dot-location
     */
    "dot-location": ["error", "property"],

    /**
     * Enforce dot notation whenever possible. 
     *
     * (fixable)
     *
     * https://eslint.org/docs/rules/dot-notation
     */
    "dot-notation": ["error", {
      "allowKeywords": true,
      "allowPattern": "",
    }],

    /**
     * Require the use of === and !==.
     *
     * https://eslint.org/docs/rules/eqeqeq
     */
    "eqeqeq": ["error", "always"],

    /**
     * Require for-in loops to include an if statement.
     *
     * https://eslint.org/docs/rules/guard-for-in
     */
    "guard-for-in": "error",

    /**
     * Enforce a maximum number of classes per file.
     *
     * https://eslint.org/docs/rules/max-classes-per-file
     */
    "max-classes-per-file": ["error", 1],
    
    /**
     * Disallow the use of alert, confirm, and prompt.
     *
     * https://eslint.org/docs/rules/no-alert
     */
    "no-alert": "error",

    /**
     * Disallow the use of arguments.caller or arguments.callee.
     *
     * https://eslint.org/docs/rules/no-caller
     */
    "no-caller": "error",

    /**
     * Disallow lexical declarations in case clauses,
     *
     * https://eslint.org/docs/rules/no-case-declarations
     */
    "no-case-declarations": "error",

    /**
     * Disallow division operators explicitly at the beginning of regular
     * expressions. 
     *
     * (fixable)
     *
     * https://eslint.org/docs/rules/no-div-regex
     */
    "no-div-regex": "error",

    /**
     * Disallow else blocks after return statements in if statements. 
     *
     * (fixable)
     *
     * https://eslint.org/docs/rules/no-else-return
     */
    "no-else-return": ["error", {
      "allowElseIf": false,
    }],

    /**
     * Disallow empty functions.
     *
     * NOTES:
     * - We sometimes use empty functions for defaultProps in react. As a
     *   result, allow functions and methods to be empty.
     *
     * https://eslint.org/docs/rules/no-empty-function
     */
    "no-empty-function": ["error", {
      "allow": [
        "functions",
        "arrowFunctions",
        //"generatorFunctions",
        "methods",
        //"generatorMethods",
        //"getters",
        //"setters",
        //"constructors",
      ]
    }],
    
    /**
     * Disallow empty destructuring patterns. 
     *
     * (fixable)
     *
     * https://eslint.org/docs/rules/no-empty-pattern
     */
    "no-empty-pattern": "error",

    /**
     * Disallow null comparisons without type-checking operators.
     *
     * https://eslint.org/docs/rules/no-eq-null
     */
    "no-eq-null": "error",

    /**
     * Disallow the use of eval().
     *
     * https://eslint.org/docs/rules/no-eval
     */
    "no-eval": ["error", {
      "allowIndirect": false,
    }],

    /**
     * Disallow extending native types.
     *
     * https://eslint.org/docs/rules/no-extend-native
     */
    "no-extend-native": ["error", {
      "exceptions": [],
    }],
    
    /**
     * Disallow unnecessary calls to .bind(). 
     *
     * (fixable)
     *
     * https://eslint.org/docs/rules/no-extra-bind
     */
    "no-extra-bind": "error",

    /**
     * Disallow unnecessary labels.
     *
     * https://eslint.org/docs/rules/no-extra-label
     */
    "no-extra-label": "error",

    /**
     * Disallow fallthrough of case statements.
     *
     * https://eslint.org/docs/rules/no-fallthrough
     */
    "no-fallthrough": ["error", {
      "commentPattern": "fallthrough",
    }],

    /**
     * Disallow leading or trailing decimal points in numeric literals.
     * 
     * (fixable)
     *
     * https://eslint.org/docs/rules/no-floating-decimal
     */
    "no-floating-decimal": "error",

    /**
     * Disallow assignments to native objects or read-only global variables.
     *
     * https://eslint.org/docs/rules/no-global-assign
     */
    "no-global-assign": ["error", {
      "exceptions": [],
    }],

    /**
     * Disallow shorthand type conversions. 
     * 
     * (fixable)
     *
     * https://eslint.org/docs/rules/no-implicit-coercion
     */
    "no-implicit-coercion": ["error", {
      "boolean": true,
      "number": true,
      "string": true,
      "allow": [
        //"~",
        //"!!",
        //"+",
        //"*",
      ]
    }],

    /**
     * Disallow variable and function declarations in the global scope.
     *
     * https://eslint.org/docs/rules/no-implicit-globals
     */
    "no-implicit-globals": "error",

    /**
     * Disallow the use of eval()-like methods.
     *
     * https://eslint.org/docs/rules/no-implied-eval
     */
    "no-implied-eval": "error",

    /**
     * Disallow this keywords outside of classes or class-like objects.
     *
     * NOTES:
     * - We use 'this' for references the global scope when we use IIFE's, etc.
     *   As a result, disable this rule.
     *
     * https://eslint.org/docs/rules/no-invalid-this
     */
    "no-invalid-this": "off",

    /**
     * Disallow the use of the __iterator__ property.
     *
     * https://eslint.org/docs/rules/no-iterator
     */
    "no-iterator": "error",

    /**
     * Disallow labeled statements.
     *
     * https://eslint.org/docs/rules/no-labels
     */
    "no-labels": ["error", {
      "allowLoop": false,
      "allowSwitch": false,
    }],

    /**
     * Disallow unnecessary nested blocks.
     *
     * https://eslint.org/docs/rules/no-lone-blocks
     */
    "no-lone-blocks": "error",

    /**
     * Disallow function declarations that contain unsafe references inside loop
     * statements.
     *
     * https://eslint.org/docs/rules/no-loop-func
     */
    "no-loop-func": "error",

    /**
     * Disallow magic numbers.
     *
     * NOTES:
     * - Setting a literal 0 will throw an error with this enabled. So, disable
     *   this rule completely.
     *
     * https://eslint.org/docs/rules/no-magic-numbers
     */
    "no-magic-numbers": ["off", {
      "ignore": [],
      "ignoreArrayIndexes": true,
      "enforceConst": true,
      "detectObjects": true,
    }],

    /**
     * Disallow multiple spaces.
     *
     * (fixable)
     *
     * https://eslint.org/docs/rules/no-multi-spaces
     */
    "no-multi-spaces": ["error", {
      "ignoreEOLComments": false,
      "exceptions": {
        "Property": false, // default is True
      }
    }],

    /**
     * Disallow multiline strings.
     *
     * https://eslint.org/docs/rules/no-multi-str
     */
    "no-multi-str": "error",
    
    /**
     * Disallow new operators outside of assignments or comparisons.
     *
     * https://eslint.org/docs/rules/no-new
     */
    // Since webpack uses plugins with new, we might need to set this to warn only
    "no-new": "warn",

    /**
     * Disallow new operators with the Function object.
     *
     * https://eslint.org/docs/rules/no-new-func
     */
    "no-new-func": 2 ,

    /**
     * Disallow new operators with the String, Number, and Boolean objects.
     *
     * https://eslint.org/docs/rules/no-new-wrappers
     */
    "no-new-wrappers": "error",

    /**
     * Disallow octal literals.
     *
     * https://eslint.org/docs/rules/no-octal
     */
    "no-octal": "error",

    /**
     * Disallow octal escape sequences in string literals.
     *
     * https://eslint.org/docs/rules/no-octal-escape
     */
    "no-octal-escape": "error",

    /**
     * Disallow reassigning function parameters.
     *
     * https://eslint.org/docs/rules/no-param-reassign
     */
    "no-param-reassign": ["error", {
      "props": true,
      "ignorePropertyModificationsFor": [
        "acc", // for reduce accumulators
        "accumulator", // for reduce accumulators
        "e", // for e.returnvalue
        "event", // for event.returnvalue
        "req", // for Express requests
        "request", // for Express requests
        "res", // for Express responses
        "response", // for Express responses
        "staticContext", // for ReactRouter context
      ],
    }],

    /**
     * Disallow the use of the __proto__ property.
     *
     * https://eslint.org/docs/rules/no-proto
     */
    "no-proto": "error",

    /**
     * Disallow variable redeclaration.
     *
     * https://eslint.org/docs/rules/no-redeclare
     */
    "no-redeclare": ["error", {
      "builtinGlobals": true,
    }],

    /**
     * Disallow certain properties on certain objects.
     *
     * https://eslint.org/docs/rules/no-restricted-properties
     */
    "no-restricted-properties": ["error", {
      object: 'arguments',
      property: 'callee',
      message: 'arguments.callee is deprecated',
    }, {
      object: 'global',
      property: 'isFinite',
      message: 'Please use Number.isFinite instead',
    }, {
      object: 'self',
      property: 'isFinite',
      message: 'Please use Number.isFinite instead',
    }, {
      object: 'window',
      property: 'isFinite',
      message: 'Please use Number.isFinite instead',
    }, {
      object: 'global',
      property: 'isNaN',
      message: 'Please use Number.isNaN instead',
    }, {
      object: 'self',
      property: 'isNaN',
      message: 'Please use Number.isNaN instead',
    }, {
      object: 'window',
      property: 'isNaN',
      message: 'Please use Number.isNaN instead',
    }, {
      property: '__defineGetter__',
      message: 'Please use Object.defineProperty instead.',
    }, {
      property: '__defineSetter__',
      message: 'Please use Object.defineProperty instead.',
    }, {
      object: 'Math',
      property: 'pow',
      message: 'Use the exponentiation operator (**) instead.',
    }],

    /**
     * Disallow assignment operators in return statements.
     *
     * https://eslint.org/docs/rules/no-return-assign
     */
    "no-return-assign": ["error", "always"],
   
    /**
     * Disallow unnecessary return await.
     *
     * https://eslint.org/docs/rules/no-return-await
     */
    "no-return-await": "error",

    /**
     * Disallow javascript: urls.
     *
     * https://eslint.org/docs/rules/no-script-url
     */
    "no-script-url": "error",

    /**
     * Disallow assignments where both sides are exactly the same.
     *
     * https://eslint.org/docs/rules/no-self-assign
     */
    "no-self-assign": ["error", {
      "props": true,
    }],

    /**
     * Disallow comparisons where both sides are exactly the same.
     *
     * https://eslint.org/docs/rules/no-self-compare
     */
    "no-self-compare": "error",

    /**
     * Disallow comma operators.
     *
     * https://eslint.org/docs/rules/no-sequences
     */
    "no-sequences": "error",

    /**
     * Disallow throwing literals as exceptions.
     *
     * https://eslint.org/docs/rules/no-throw-literal
     */
    "no-throw-literal": "error",

    /**
     * Disallow unmodified loop conditions.
     *
     * https://eslint.org/docs/rules/no-unmodified-loop-condition
     */
    "no-unmodified-loop-condition": "error",

    /**
     * Disallow unused expressions.
     *
     * https://eslint.org/docs/rules/no-unused-expressions
     */
    "no-unused-expressions": ["error", {
      "allowShortCircuit": false,
      "allowTernary": false,
      "allowTaggedTemplates": false
    }],

    /**
     * Disallow unused labels.
     *
     * (fixable)
     *
     * https://eslint.org/docs/rules/no-unused-labels
     */
    "no-unused-labels": "error",

    /**
     * Disallow unnecessary calls to .call() and .apply().
     *
     * NOTES:
     * - Sometimes, .call() and .apply() are used to invoke a function with a
     *   specific context/arguments. As a result, disable this rule.
     *
     * https://eslint.org/docs/rules/no-useless-call
     */
    "no-useless-call": "off",

    /**
     * Disallow unnecessary catch clauses,
     *
     * https://eslint.org/docs/rules/no-useless-catch
     */
    "no-useless-catch": "error",

    /**
     * Disallow unnecessary concatenation of literals or template literals.
     *
     * https://eslint.org/docs/rules/no-useless-concat
     */
    "no-useless-concat": "error",

    /**
     * Disallow unnecessary escape characters.
     *
     * https://eslint.org/docs/rules/no-useless-escape
     */
    "no-useless-escape": "error",

    /**
     * Disallow redundant return statements.
     *
     * (fixable)
     *
     * https://eslint.org/docs/rules/no-useless-return
     */
    "no-useless-return": "error",
   
    /**
     * Disallow void operators,
     *
     * https://eslint.org/docs/rules/no-void
     */
    "no-void": "error",

    /**
     * Disallow specified warning terms in comments.
     *
     * https://eslint.org/docs/rules/no-warning-comments
     */
    "no-warning-comments": ["error", {
      "terms": ["todo", "fix",],
      "location": "start",
    }],

    /**
     * Disallow with statements.
     *
     * https://eslint.org/docs/rules/no-with
     */
    "no-with": "error",

    /**
     * Enforce using named capture group in regular expression.
     *
     * NOTES:
     * - This is only available in newer ecmascript version.
     *
     * https://eslint.org/docs/rules/prefer-named-capture-group
     */
    "prefer-named-capture-group": "off",
    
    /**
     * Require using Error objects as Promise rejection reasons.
     * 
     * https://eslint.org/docs/rules/prefer-promise-reject-errors
     */
    "prefer-promise-reject-errors": "error",

    /**
     * Enforce the consistent use of the radix argument when using parseInt().
     *
     * https://eslint.org/docs/rules/radix
     */
    "radix": ["error", "as-needed"],

    /**
     * Disallow async functions which have no await expression.
     *
     * NOTES:
     * - Disabled this according to AirBNB eslint.
     *
     * https://eslint.org/docs/rules/require-await
     */
    "require-await": "off",

    /**
     * Enforce the use of u flag on RegExp.
     *
     * https://eslint.org/docs/rules/require-unicode-regexp
     */
    "require-unicode-regexp": "off",
   
    /**
     * Require var declarations be placed at the top of their containing scope.
     *
     * https://eslint.org/docs/rules/vars-on-top
     */
    "vars-on-top": "error",

    /**
     * Require parentheses around immediate function invocations.
     *
     * https://eslint.org/docs/rules/wrap-iife
     */
    "wrap-iife": ["error", "outside", {
      "functionPrototypeMethods": false
    }],

    /**
     * Require or disallow “Yoda” conditions.
     *
     * https://eslint.org/docs/rules/yoda
     */
    "yoda": ["error", "never", {
      "exceptRange": true,
      "onlyEquality": false,
    }],
  }
}