type-fest Files

Breaking

• This package is now pure ESM. Please read this.
• Require TypeScript 5.9 b5b0214
• Require Node.js 20 cc2b0f2
• Reminder: type-fest requires strict: true in your tsconfig.
• StringKeyOf: Rename to KeyAsString e492c9c
• ArrayTail: Enable preserveReadonly by default and remove the option b34b1d8
• CamelCase / CamelCasedProperties / CamelCasedPropertiesDeep / PascalCase / PascalCasedProperties / PascalCasedPropertiesDeep: Disable preserveConsecutiveUppercase by default 8226c1b
• This aligns it with the general JavaScript naming convention.
• PartialDeep: Disable allowUndefinedInNonTupleArrays by default b3c4524
• Split: Enable strictLiteralChecks by default 544a846
• Paths: Default maxRecursionDepth 5 (was 10) 2ab5dec
• ObservableLike: Move to sub-export 2a1072e
• Deprecate If* types in favor of a single If 4c2151a

New types

• Alphanumeric — Single alphanumeric character (A–Z, a–z, 0–9). 484e030
• AllExtend — Evaluates to true if every element of a tuple/array extends U. c8c6d55
• ConditionalSimplify — Simplifies a type’s unions/intersections with opt-in controls. b7a4771
• ConditionalSimplifyDeep — Deep version of ConditionalSimplify that recurses into objects. b7a4771
• DigitCharacter — Single ASCII digit character (0–9). 484e030
• ExcludeStrict — Non-distributive, stricter variant of Exclude<T, U>. e6f62a2
• ExtendsStrict — Non-distributive A extends B check. d71242a
• ExtractStrict — Non-distributive, stricter variant of Extract<T, U>. 98d24fa
• IsLowercase — Evaluates to true if a string literal is all lowercase. afe132c
• IsNullable — Evaluates to true if T includes null. 5067e25
• IsOptional — Evaluates to true if T includes undefined. 5067e25
• IsOptionalKeyOf — Evaluates to true if property K of T is optional. 93728b5
• IsReadonlyKeyOf — Evaluates to true if property K of T is readonly. 93728b5
• IsRequiredKeyOf — Evaluates to true if property K of T is required. 93728b5
• IsUnion — Evaluates to true if T is a union type. b3d92ed
• IsUndefined — Evaluates to true if the type is exactly undefined. f7bc576
• IsUppercase — Evaluates to true if a string literal is all uppercase. afe132c
• LowercaseLetter — Single lowercase Latin letter (a–z). 484e030
• RemovePrefix — Removes a specified prefix from a string literal. 18a1c04
• UppercaseLetter — Single uppercase Latin letter (A–Z). 484e030

Improvements

• Jsonify: Handle unknown as JsonValue 642bb13
• SetRequired / SetOptional / SetReadonly: Handle functions with properties a5e45d4
• Schema: Preserve arrays/remove extraneous unions 8a96def; drop undefined for recurseIntoArrays 1cb955b
• ReadonlyKeysOf / WritableKeysOf: Add object constraint a6efbe0
• TsConfigJson: Add TypeScript 5.9 fields d2bda94

Fixes

• Or: Fix with boolean, never, any 42d6106
• And: Fix with boolean, never, any b38ac60
• IsStringLiteral: Fix uncollapsed unions, and tagged types eb37799 / d1b35c7
• Paths: Fix behavior with index signatures 9926e5d
• ConditionalKeys: Fix behavior with arrays and unions 4d7cc50
• RequiredDeep: Fix with undefined bfcdbc4
• Split: Fix template strings ending with interpolation 853b881
• ArrayTail: Fix fix non-tuple arrays f3aabd8
• Fix UnionMin and UnionMax d52d5e7

Meta

Huge thanks to all the contributors to this release, especially @som-sm 🙌

https://github.com/sindresorhus/type-fest/compare/v4.41.0...v5.0.0