eslint-config-noftalint/rules/typescript.js

Noftaly's eslint configuration

module.exports = {
  plugins: ['@typescript-eslint/eslint-plugin'],

  rules: {
    // Require that member overloads be consecutive
    '@typescript-eslint/adjacent-overload-signatures': 'error',

    // Requires using either T[] or Array<T> for arrays
    '@typescript-eslint/array-type': ['error', { default: 'array-simple' }],

    // Disallows awaiting a value that is not a Thenable
    '@typescript-eslint/await-thenable': 'error',

    // Bans @ts-<directive> comments from being used or requires descriptions after directive
    '@typescript-eslint/ban-ts-comment': ['error', {
      'ts-expect-error': 'allow-with-description',
      'ts-ignore': true,
      'ts-nocheck': true,
      'ts-check': false,
      minimumDescriptionLength: 5,
    }],

    // Bans // tslint:<rule-flag> comments from being used
    '@typescript-eslint/ban-tslint-comment': 'error',

    // Bans specific types from being used
    '@typescript-eslint/ban-types': ['error', { extendDefaults: true }],

    // Ensures that literals on classes are exposed in a consistent style
    '@typescript-eslint/class-literal-property-style': ['error', 'fields'],

    // Enforces specifying generic type arguments on type annotation or constructor name of a constructor call
    '@typescript-eslint/consistent-generic-constructors': ['error', 'constructor'],

    // Enforce or disallow the use of the record type
    '@typescript-eslint/consistent-indexed-object-style': ['error', 'record'],

    // Enforces consistent usage of type assertions
    '@typescript-eslint/consistent-type-assertions': ['error', {
      assertionStyle: 'as',
      objectLiteralTypeAssertions: 'allow',
    }],

    // Consistent with type definition either interface or type
    '@typescript-eslint/consistent-type-definitions': ['error', 'interface'],

    // Enforces consistent usage of type exports
    '@typescript-eslint/consistent-type-exports': 'error',

    // Enforces consistent usage of type imports
    '@typescript-eslint/consistent-type-imports': ['error', {
      prefer: 'type-imports',
      disallowTypeAnnotations: true,
    }],

    // Require explicit return types on functions and class methods
    '@typescript-eslint/explicit-function-return-type': ['error', {
      allowExpressions: false,
      allowTypedFunctionExpressions: true,
      allowHigherOrderFunctions: true,
      allowDirectConstAssertionInArrowFunctions: true,
      allowConciseArrowFunctionExpressionsStartingWithVoid: false,
    }],

    // Require explicit accessibility modifiers on class properties and methods
    '@typescript-eslint/explicit-member-accessibility': ['error', {
      accessibility: 'explicit',
      overrides: {
        accessors: 'explicit',
        constructors: 'no-public',
        methods: 'explicit',
        properties: 'off',
        parameterProperties: 'explicit',
      },
    }],

    // Require explicit return and argument types on exported functions' and classes' public class methods
    '@typescript-eslint/explicit-module-boundary-types': ['error', {
      allowArgumentsExplicitlyTypedAsAny: false,
      allowDirectConstAssertionInArrowFunctions: true,
      allowedNames: [],
      allowHigherOrderFunctions: true,
      allowTypedFunctionExpressions: true,
    }],

    // Require a specific member delimiter style for interfaces and type literals
    '@typescript-eslint/member-delimiter-style': ['error', {
      multiline: {
        delimiter: 'semi',
        requireLast: true,
      },
      singleline: {
        delimiter: 'semi',
        requireLast: false,
      },
    }],

    // Require a consistent member declaration order
    '@typescript-eslint/member-ordering': ['error', {
      default: {
        memberTypes: [
          // Index signature
          'signature',

          // Fields
          'public-static-field',
          'protected-static-field',
          'private-static-field',
          '#private-static-field',

          'public-decorated-field',
          'protected-decorated-field',
          'private-decorated-field',

          'public-instance-field',
          'protected-instance-field',
          'private-instance-field',
          '#private-instance-field',

          'public-abstract-field',
          'protected-abstract-field',

          'public-field',
          'protected-field',
          'private-field',
          '#private-field',

          'static-field',
          'instance-field',
          'abstract-field',

          'decorated-field',

          'field',

          // Static initialization
          'static-initialization',

          // Constructors
          'public-constructor',
          'protected-constructor',
          'private-constructor',

          'constructor',

          // Methods
          'public-static-method',
          'protected-static-method',
          'private-static-method',
          '#private-static-method',

          'public-instance-method',
          'protected-instance-method',
          'private-instance-method',
          '#private-instance-method',

          'public-abstract-method',
          'protected-abstract-method',

          'public-method',
          'protected-method',
          'private-method',
          '#private-method',

          'static-method',
          'instance-method',
          'abstract-method',

          'method',
        ],
        order: 'as-written',
      },
    }],

    // Enforces using a particular method signature syntax
    '@typescript-eslint/method-signature-style': 'off',

    // Enforces naming conventions for everything across a codebase
    '@typescript-eslint/naming-convention': [
      'error',
      {
        selector: 'default',
        format: ['camelCase'],
        leadingUnderscore: 'allow',
        trailingUnderscore: 'allow',
      },
      {
        selector: 'variable',
        format: ['camelCase', 'UPPER_CASE', 'PascalCase'],
        leadingUnderscore: 'allow',
        trailingUnderscore: 'allow',
      },
      {
        selector: 'objectLiteralProperty',
        format: ['camelCase', 'UPPER_CASE'],
        leadingUnderscore: 'allow',
        trailingUnderscore: 'allow',
      },
      {
        selector: 'memberLike',
        modifiers: ['private'],
        format: ['camelCase'],
        leadingUnderscore: 'require',
        trailingUnderscore: 'allow',
      },
      {
        selector: 'memberLike',
        modifiers: ['static'],
        format: ['camelCase', 'UPPER_CASE'],
        leadingUnderscore: 'forbid',
        trailingUnderscore: 'allow',
      },
      {
        selector: 'enumMember',
        format: ['PascalCase'],
        leadingUnderscore: 'forbid',
        trailingUnderscore: 'allow',
      },
      {
        selector: 'interface',
        format: ['PascalCase'],
        custom: {
          regex: '^I[A-Z]',
          match: false,
        },
      },
      {
        selector: 'import',
        format: ['camelCase', 'PascalCase'],
        leadingUnderscore: 'allow',
        trailingUnderscore: 'allow',
      },
      {
        selector: 'typeLike',
        format: ['PascalCase'],
        leadingUnderscore: 'forbid',
        trailingUnderscore: 'allow',
      },
    ],

    // Disallow using the `delete` operator on array values.
    '@typescript-eslint/no-array-delete': 'error',

    // Requires that .toString() is only called on objects which provide useful information when stringified
    '@typescript-eslint/no-base-to-string': ['error', {
      ignoredTypeNames: ['RegExp'],
    }],

    // Disallow non-null assertion in locations that may be confusing
    '@typescript-eslint/no-confusing-non-null-assertion': 'error',

    // Requires expressions of type void to appear in statement position
    '@typescript-eslint/no-confusing-void-expression': 'error',

    // Disallow duplicate enum member values
    '@typescript-eslint/no-duplicate-enum-values': 'error',

    // Disallow duplicate constituents of union or intersection types.
    '@typescript-eslint/no-duplicate-type-constituents': 'error',

    // Disallow the delete operator with computed key expressions
    '@typescript-eslint/no-dynamic-delete': 'error',

    // Disallow the declaration of empty interfaces
    '@typescript-eslint/no-empty-interface': 'error',

    // Disallow usage of the any type
    '@typescript-eslint/no-explicit-any': ['error', { ignoreRestArgs: true }],

    // Disallow extra non-null assertion
    '@typescript-eslint/no-extra-non-null-assertion': 'error',

    // Forbids the use of classes as namespaces
    '@typescript-eslint/no-extraneous-class': ['error', {
      allowConstructorOnly: false,
      allowEmpty: false,
      allowStaticOnly: false,
      allowWithDecorator: true,
    }],

    // Requires Promise-like values to be handled appropriately
    '@typescript-eslint/no-floating-promises': ['error', {
      ignoreVoid: true,
      ignoreIIFE: false,
    }],

    // Disallow iterating over an array with a for-in loop
    '@typescript-eslint/no-for-in-array': 'error',

    // Disallow the use of eval()-like methods
    'no-implied-eval': 'off',
    '@typescript-eslint/no-implied-eval': 'error',

    // Enforce the use of top-level import type qualifier when an import only has specifiers with inline type qualifiers
    '@typescript-eslint/no-import-type-side-effects': 'error',

    // Disallows explicit type declarations for variables or parameters initialized to a number, string, or boolean
    '@typescript-eslint/no-inferrable-types': 'error',

    // Disallows usage of void type outside of generic or return types
    '@typescript-eslint/no-invalid-void-type': ['error', {
      allowInGenericTypeArguments: true,
      allowAsThisParameter: true,
    }],

    // Disallow the void operator except when used to discard a value
    '@typescript-eslint/no-meaningless-void-operator': 'error',

    // Enforce valid definition of new and constructor
    '@typescript-eslint/no-misused-new': 'error',

    // Avoid using promises in places not designed to handle them
    '@typescript-eslint/no-misused-promises': ['error', {
      checksConditionals: true,
      checksVoidReturn: false,
    }],

    // Disallow enums from having both number and string members.
    '@typescript-eslint/no-mixed-enums': 'error',

    // Disallow the use of custom TypeScript modules and namespaces
    '@typescript-eslint/no-namespace': ['error', {
      allowDeclarations: false,
      allowDefinitionFiles: true,
    }],

    // Disallows using a non-null assertion after an optional chain expression
    '@typescript-eslint/no-non-null-asserted-nullish-coalescing': 'error',

    // Disallows using a non-null assertion after an optional chain expression
    '@typescript-eslint/no-non-null-asserted-optional-chain': 'error',

    // Disallows non-null assertions using the ! postfix operator
    '@typescript-eslint/no-non-null-assertion': 'off',

    // Disallow members of unions and intersections that do nothing or override type information.
    '@typescript-eslint/no-redundant-type-constituents': 'error',

    // Disallows invocation of require()
    // Already set with import/no-commonjs
    '@typescript-eslint/no-require-imports': 'off',

    // Disallow aliasing this
    '@typescript-eslint/no-this-alias': ['error', {
      allowDestructuring: true,
      allowedNames: [],
    }],

    // Disallow throwing literals as exceptions
    'no-throw-literal': 'off',
    '@typescript-eslint/only-throw-error': 'error',

    // Flags unnecessary equality comparisons against boolean literals
    '@typescript-eslint/no-unnecessary-boolean-literal-compare': 'error',

    // Prevents conditionals where the type is always truthy or always falsy
    // Disabled because I had some issued with it (false positive).
    '@typescript-eslint/no-unnecessary-condition': 'off',

    // Warns when a namespace qualifier is unnecessary
    '@typescript-eslint/no-unnecessary-qualifier': 'error',

    // Enforces that type arguments will not be used if not required
    '@typescript-eslint/no-unnecessary-type-arguments': 'error',

    // Warns if a type assertion does not change the type of an expression
    '@typescript-eslint/no-unnecessary-type-assertion': 'error',

    // Disallows unnecessary constraints on generic types
    '@typescript-eslint/no-unnecessary-type-constraint': 'error',

    // Disallows calling an function with an any type value
    '@typescript-eslint/no-unsafe-argument': 'error',

    // Disallows assigning any to variables and properties
    '@typescript-eslint/no-unsafe-assignment': 'off',

    // Disallows calling an any type value
    '@typescript-eslint/no-unsafe-call': 'off',

    // Disallow unsafe declaration merging
    '@typescript-eslint/no-unsafe-declaration-merging': 'error',

    // Disallow comparing an enum value with a non-enum value.
    '@typescript-eslint/no-unsafe-enum-comparison': 'error',

    // Disallows member access on any typed variables
    '@typescript-eslint/no-unsafe-member-access': 'off',

    // Disallows returning any from a function
    '@typescript-eslint/no-unsafe-return': 'off',

    // Require unary negation to take a number.
    '@typescript-eslint/no-unsafe-unary-minus': 'error',

    // Disallow empty exports that don't change anything in a module file.
    '@typescript-eslint/no-useless-empty-export': 'error',

    // Disallow unnecessary template literals.
    '@typescript-eslint/no-useless-template-literals': 'error',

    // Disallows the use of require statements except in import statements
    // Already set with import/no-commonjs + We don't want `import x = require()`
    '@typescript-eslint/no-var-requires': 'off',

    // Prefers a non-null assertion over explicit type cast when possible
    '@typescript-eslint/non-nullable-type-assertion-style': 'error',

    // Require or disallow the use of parameter properties in class constructors.
    '@typescript-eslint/parameter-properties': 'off',

    // Prefer usage of as const over literal type
    '@typescript-eslint/prefer-as-const': 'error',

    // Prefer initializing each enums member value
    '@typescript-eslint/prefer-enum-initializers': 'off',

    // Enforce the use of Array.prototype.find() over Array.prototype.filter()[0] when looking for a single result.
    '@typescript-eslint/prefer-find': 'error',
    'unicorn/prefer-array-find': 'off',

    // Prefer a ‘for-of’ loop over a standard ‘for’ loop if the index is only used to access the array being iterated
    '@typescript-eslint/prefer-for-of': 'off',

    // Use function types instead of interfaces with call signatures
    '@typescript-eslint/prefer-function-type': 'error',

    // Enforce includes method over indexOf method
    '@typescript-eslint/prefer-includes': 'error',

    // Require that all enum members be literal values to prevent unintended enum member name shadow issues
    '@typescript-eslint/prefer-literal-enum-member': ['error', { allowBitwiseExpressions: true }],

    // Require the use of the namespace keyword instead of the module keyword to declare custom TypeScript modules
    '@typescript-eslint/prefer-namespace-keyword': 'error',

    // Enforce the usage of the nullish coalescing operator instead of logical chaining
    '@typescript-eslint/prefer-nullish-coalescing': ['error', { ignoreConditionalTests: true }],

    // Prefer using concise optional chain expressions instead of chained logical ands
    '@typescript-eslint/prefer-optional-chain': 'error',

    // Require using Error objects as Promise rejection reasons.
    '@typescript-eslint/prefer-promise-reject-errors': 'error',

    // Requires that private members are marked as readonly if they're never modified outside of the constructor
    '@typescript-eslint/prefer-readonly': 'error',

    // Requires that function parameters are typed as readonly to prevent accidental mutation of inputs
    '@typescript-eslint/prefer-readonly-parameter-types': 'off',

    // Prefer using type parameter when calling Array#reduce instead of casting
    '@typescript-eslint/prefer-reduce-type-parameter': 'error',

    // Enforce that RegExp#exec is used instead of String#match if no global flag is provided
    '@typescript-eslint/prefer-regexp-exec': 'error',

    // Enforce that this is used when only this type is returned
    '@typescript-eslint/prefer-return-this-type': 'error',

    // Enforce the use of String#startsWith and String#endsWith instead of other equivalent
    // methods of checking substrings
    '@typescript-eslint/prefer-string-starts-ends-with': 'error',

    // Recommends using @ts-expect-error over @ts-ignore
    '@typescript-eslint/prefer-ts-expect-error': 'error',

    // Requires any function or method that returns a Promise to be marked async
    '@typescript-eslint/promise-function-async': 'error',

    // Requires Array#sort calls to always provide a compareFunction
    '@typescript-eslint/require-array-sort-compare': ['error', { ignoreStringArrays: true }],

    // When adding two variables, operands must both be of type number or of type string
    '@typescript-eslint/restrict-plus-operands': 'error',

    // Enforce template literal expressions to be of string type
    '@typescript-eslint/restrict-template-expressions': 'off',

    // Enforce constituents of a type union/intersection to be sorted alphabetically
    '@typescript-eslint/sort-type-constituents': 'error',

    // Restricts the types allowed in boolean expressions
    // Requires `strictNullChecks` to work.
    '@typescript-eslint/strict-boolean-expressions': 'off',

    // Exhaustiveness checking in switch with union type
    '@typescript-eslint/switch-exhaustiveness-check': 'error',

    // Sets preference level for triple slash directives versus ES6-style import declarations
    '@typescript-eslint/triple-slash-reference': 'error',

    // Require consistent spacing around type annotations
    '@typescript-eslint/type-annotation-spacing': 'error',

    // Requires type annotations to exist
    '@typescript-eslint/typedef': 'off',

    // Enforces unbound methods are called with their expected scope
    '@typescript-eslint/unbound-method': 'error',

    // Warns for any two overloads that could be unified into one by using a union or an optional/rest parameter
    '@typescript-eslint/unified-signatures': 'error',

    // Enforce typing arguments in `.catch()` callbacks as `unknown`.
    '@typescript-eslint/use-unknown-in-catch-callback-variable': 'error',
  },
};