A collection of essential TypeScript types


Keywords
typescript, ts, types, utility, util, utilities, omit, merge, json, npm-package, typescript-definitions
License
MIT
Install
npm install type-fest@0.5.2

Documentation



type-fest

A collection of essential TypeScript types



Build Status

Many of the types here should have been built-in. You can help by suggesting some of them to the TypeScript project.

Either add this package as a dependency or copy-paste the needed types. No credit required. 👌

PR welcome for additional commonly needed types and docs improvements. Read the contributing guidelines first.

Install

$ npm install type-fest

Requires TypeScript >=3.2

Usage

import {Omit} from 'type-fest';

type Foo = {
	unicorn: string;
	rainbow: boolean;
};

type FooWithoutRainbow = Omit<Foo, 'rainbow'>;
//=> {unicorn: string}

API

Click the type names for complete docs.

Basic

Utilities

  • Omit - Create a type from an object type without certain keys.
  • Mutable - Convert an object with readonly properties into a mutable object. Inverse of Readonly<T>.
  • Merge - Merge two types into a new type. Keys of the second type overrides keys of the first type.
  • MergeExclusive - Create a type that has mutually exclusive properties.
  • RequireAtLeastOne - Create a type that requires at least one of the given properties.
  • ReadonlyDeep - Create a deeply immutable version of a object/Map/Set/Array type.
  • LiteralUnion - Create a union type by combining primitive types and literal types without sacrificing auto-completion in IDEs for the literal type part of the union. Workaround for Microsoft/TypeScript#29729.

Miscellaneous

Declined types

If we decline a type addition, we will make sure to document the better solution here.

  • Diff and Spread - The PR author didn't provide any real-world use-cases and the PR went stale. If you think this type is useful, provide some real-world use-cases and we might reconsider.

Tips

Built-in types

There are many advanced types most users don't know about.

You can find some examples in the TypeScript docs.

Maintainers

License

(MIT OR CC0-1.0)