---
title: Strict preset
---

# 🔴 Strict

Use when you want recommended-type-checked + additional stable runtime helpers.

## Config key

```ts
typefest.configs.strict;
```

## Flat Config example

```ts
import typefest from "eslint-plugin-typefest";

export default [typefest.configs.strict];
```

## Rules in this preset

- `Fix` legend:
  - `🔧` = autofixable
  - `💡` = suggestions available
  - `—` = report only

| Rule                                                                                                                                              |  Fix  |
| ------------------------------------------------------------------------------------------------------------------------------------------------- | :---: |
| [`prefer-ts-extras-array-at`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-ts-extras-array-at)                           |  🔧   |
| [`prefer-ts-extras-array-concat`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-ts-extras-array-concat)                   |  🔧   |
| [`prefer-ts-extras-array-first`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-ts-extras-array-first)                     | 🔧 💡 |
| [`prefer-ts-extras-array-includes`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-ts-extras-array-includes)               | 🔧 💡 |
| [`prefer-ts-extras-array-join`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-ts-extras-array-join)                       |  🔧   |
| [`prefer-ts-extras-array-last`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-ts-extras-array-last)                       | 🔧 💡 |
| [`prefer-ts-extras-as-writable`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-ts-extras-as-writable)                     |  🔧   |
| [`prefer-ts-extras-assert-defined`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-ts-extras-assert-defined)               | 🔧 💡 |
| [`prefer-ts-extras-assert-error`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-ts-extras-assert-error)                   |  💡   |
| [`prefer-ts-extras-assert-never`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-ts-extras-assert-never)                   |  💡   |
| [`prefer-ts-extras-assert-present`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-ts-extras-assert-present)               | 🔧 💡 |
| [`prefer-ts-extras-is-defined`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-ts-extras-is-defined)                       |  🔧   |
| [`prefer-ts-extras-is-defined-filter`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-ts-extras-is-defined-filter)         |  🔧   |
| [`prefer-ts-extras-is-empty`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-ts-extras-is-empty)                           |  🔧   |
| [`prefer-ts-extras-is-finite`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-ts-extras-is-finite)                         |  🔧   |
| [`prefer-ts-extras-is-infinite`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-ts-extras-is-infinite)                     |  🔧   |
| [`prefer-ts-extras-is-integer`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-ts-extras-is-integer)                       |  🔧   |
| [`prefer-ts-extras-is-present`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-ts-extras-is-present)                       |  🔧   |
| [`prefer-ts-extras-is-present-filter`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-ts-extras-is-present-filter)         |  🔧   |
| [`prefer-ts-extras-is-property-defined`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-ts-extras-is-property-defined)     |  🔧   |
| [`prefer-ts-extras-is-property-present`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-ts-extras-is-property-present)     |  🔧   |
| [`prefer-ts-extras-is-safe-integer`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-ts-extras-is-safe-integer)             |  🔧   |
| [`prefer-ts-extras-key-in`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-ts-extras-key-in)                               |  🔧   |
| [`prefer-ts-extras-not`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-ts-extras-not)                                     |  🔧   |
| [`prefer-ts-extras-object-entries`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-ts-extras-object-entries)               |  🔧   |
| [`prefer-ts-extras-object-from-entries`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-ts-extras-object-from-entries)     |  🔧   |
| [`prefer-ts-extras-object-has-in`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-ts-extras-object-has-in)                 | 🔧 💡 |
| [`prefer-ts-extras-object-has-own`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-ts-extras-object-has-own)               | 🔧 💡 |
| [`prefer-ts-extras-object-keys`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-ts-extras-object-keys)                     |  🔧   |
| [`prefer-ts-extras-object-values`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-ts-extras-object-values)                 |  🔧   |
| [`prefer-ts-extras-safe-cast-to`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-ts-extras-safe-cast-to)                   |  🔧   |
| [`prefer-ts-extras-set-has`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-ts-extras-set-has)                             | 🔧 💡 |
| [`prefer-ts-extras-string-split`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-ts-extras-string-split)                   |  🔧   |
| [`prefer-type-fest-absolute`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-type-fest-absolute)                           |  🔧   |
| [`prefer-type-fest-abstract-constructor`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-type-fest-abstract-constructor)   |  🔧   |
| [`prefer-type-fest-and`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-type-fest-and)                                     |  🔧   |
| [`prefer-type-fest-and-all`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-type-fest-and-all)                             |  🔧   |
| [`prefer-type-fest-array-element`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-type-fest-array-element)                 |  🔧   |
| [`prefer-type-fest-array-length`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-type-fest-array-length)                   |  🔧   |
| [`prefer-type-fest-array-values`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-type-fest-array-values)                   |  🔧   |
| [`prefer-type-fest-arrayable`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-type-fest-arrayable)                         |  🔧   |
| [`prefer-type-fest-async-return-type`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-type-fest-async-return-type)         |  🔧   |
| [`prefer-type-fest-conditional-pick`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-type-fest-conditional-pick)           |  🔧   |
| [`prefer-type-fest-conditional-pick-deep`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-type-fest-conditional-pick-deep) |  🔧   |
| [`prefer-type-fest-constructor`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-type-fest-constructor)                     |  🔧   |
| [`prefer-type-fest-entries`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-type-fest-entries)                             |  🔧   |
| [`prefer-type-fest-entry`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-type-fest-entry)                                 |  🔧   |
| [`prefer-type-fest-except`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-type-fest-except)                               |  🔧   |
| [`prefer-type-fest-extract-rest-element`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-type-fest-extract-rest-element)   |  🔧   |
| [`prefer-type-fest-has-optional-keys`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-type-fest-has-optional-keys)         |  🔧   |
| [`prefer-type-fest-has-readonly-keys`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-type-fest-has-readonly-keys)         |  🔧   |
| [`prefer-type-fest-has-required-keys`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-type-fest-has-required-keys)         |  🔧   |
| [`prefer-type-fest-has-writable-keys`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-type-fest-has-writable-keys)         |  🔧   |
| [`prefer-type-fest-if`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-type-fest-if)                                       |  🔧   |
| [`prefer-type-fest-is-any`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-type-fest-is-any)                               |  🔧   |
| [`prefer-type-fest-is-never`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-type-fest-is-never)                           |  🔧   |
| [`prefer-type-fest-is-null`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-type-fest-is-null)                             |  🔧   |
| [`prefer-type-fest-is-nullable`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-type-fest-is-nullable)                     |  🔧   |
| [`prefer-type-fest-is-tuple`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-type-fest-is-tuple)                           |  🔧   |
| [`prefer-type-fest-is-undefined`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-type-fest-is-undefined)                   |  🔧   |
| [`prefer-type-fest-is-unknown`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-type-fest-is-unknown)                       |  🔧   |
| [`prefer-type-fest-iterable-element`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-type-fest-iterable-element)           |  🔧   |
| [`prefer-type-fest-json-array`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-type-fest-json-array)                       |  🔧   |
| [`prefer-type-fest-json-object`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-type-fest-json-object)                     |  🔧   |
| [`prefer-type-fest-json-primitive`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-type-fest-json-primitive)               |  🔧   |
| [`prefer-type-fest-json-value`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-type-fest-json-value)                       |  💡   |
| [`prefer-type-fest-keys-of-union`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-type-fest-keys-of-union)                 |  🔧   |
| [`prefer-type-fest-less-than`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-type-fest-less-than)                         |  🔧   |
| [`prefer-type-fest-less-than-or-equal`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-type-fest-less-than-or-equal)       |  🔧   |
| [`prefer-type-fest-literal-union`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-type-fest-literal-union)                 |  🔧   |
| [`prefer-type-fest-merge-exclusive`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-type-fest-merge-exclusive)             |  🔧   |
| [`prefer-type-fest-non-empty-tuple`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-type-fest-non-empty-tuple)             |  🔧   |
| [`prefer-type-fest-non-nullable-deep`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-type-fest-non-nullable-deep)         |  🔧   |
| [`prefer-type-fest-omit-index-signature`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-type-fest-omit-index-signature)   |  🔧   |
| [`prefer-type-fest-optional`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-type-fest-optional)                           |  🔧   |
| [`prefer-type-fest-optional-keys-of`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-type-fest-optional-keys-of)           |  🔧   |
| [`prefer-type-fest-or`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-type-fest-or)                                       |  🔧   |
| [`prefer-type-fest-or-all`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-type-fest-or-all)                               |  🔧   |
| [`prefer-type-fest-partial-deep`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-type-fest-partial-deep)                   |  🔧   |
| [`prefer-type-fest-primitive`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-type-fest-primitive)                         |  🔧   |
| [`prefer-type-fest-promisable`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-type-fest-promisable)                       |  🔧   |
| [`prefer-type-fest-readonly-deep`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-type-fest-readonly-deep)                 |  🔧   |
| [`prefer-type-fest-readonly-keys-of`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-type-fest-readonly-keys-of)           |  🔧   |
| [`prefer-type-fest-require-all-or-none`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-type-fest-require-all-or-none)     |  🔧   |
| [`prefer-type-fest-require-at-least-one`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-type-fest-require-at-least-one)   |  🔧   |
| [`prefer-type-fest-require-exactly-one`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-type-fest-require-exactly-one)     |  🔧   |
| [`prefer-type-fest-require-one-or-none`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-type-fest-require-one-or-none)     |  🔧   |
| [`prefer-type-fest-required-deep`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-type-fest-required-deep)                 |  🔧   |
| [`prefer-type-fest-required-keys-of`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-type-fest-required-keys-of)           |  🔧   |
| [`prefer-type-fest-schema`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-type-fest-schema)                               |  🔧   |
| [`prefer-type-fest-set-non-nullable`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-type-fest-set-non-nullable)           |  🔧   |
| [`prefer-type-fest-set-optional`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-type-fest-set-optional)                   |  🔧   |
| [`prefer-type-fest-set-readonly`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-type-fest-set-readonly)                   |  🔧   |
| [`prefer-type-fest-set-required`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-type-fest-set-required)                   |  🔧   |
| [`prefer-type-fest-simplify`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-type-fest-simplify)                           |  🔧   |
| [`prefer-type-fest-tagged-brands`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-type-fest-tagged-brands)                 |  🔧   |
| [`prefer-type-fest-tuple-of`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-type-fest-tuple-of)                           |  🔧   |
| [`prefer-type-fest-union-length`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-type-fest-union-length)                   |  🔧   |
| [`prefer-type-fest-union-member`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-type-fest-union-member)                   |  🔧   |
| [`prefer-type-fest-union-to-tuple`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-type-fest-union-to-tuple)               |  🔧   |
| [`prefer-type-fest-unknown-array`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-type-fest-unknown-array)                 |  🔧   |
| [`prefer-type-fest-unknown-map`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-type-fest-unknown-map)                     |  🔧   |
| [`prefer-type-fest-unknown-record`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-type-fest-unknown-record)               |  🔧   |
| [`prefer-type-fest-unknown-set`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-type-fest-unknown-set)                     |  🔧   |
| [`prefer-type-fest-unwrap-tagged`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-type-fest-unwrap-tagged)                 |  🔧   |
| [`prefer-type-fest-value-of`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-type-fest-value-of)                           |  🔧   |
| [`prefer-type-fest-writable`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-type-fest-writable)                           |  🔧   |
| [`prefer-type-fest-writable-deep`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-type-fest-writable-deep)                 |  🔧   |
| [`prefer-type-fest-writable-keys-of`](https://nick2bad4u.github.io/eslint-plugin-typefest/docs/rules/prefer-type-fest-writable-keys-of)           |  🔧   |