type-fest

What is type-fest?

The type-fest package provides a collection of essential TypeScript types for use in a wide range of applications. It includes utility types, primitive types, and complex object types to enhance TypeScript's static typing capabilities.

What are type-fest's main functionalities?

Primitive types

Includes types like LiteralUnion, Primitive, and Promisable, which help with defining literals, primitive values, and promise-like structures.

{"isPrimitive": true}

Basic utilities

Provides utility types such as Except, Mutable, ReadonlyDeep, and many others that help manipulate and transform types in various ways.

{"isEmptyArray": array.length === 0}

Object types

Contains types for working with objects, such as Merge and RequireAtLeastOne, which assist in merging types and ensuring at least one property is present, respectively.

{"isObjectClean": Object.keys(object).length === 0 && object.constructor === Object}

Conditional types

Includes conditional types like ConditionalExcept and ConditionalKeys, which apply conditions to filter keys or properties of types.

{"isTruthy": T extends false | '' | 0 | null | undefined ? false : true}

Other packages similar to type-fest

utility-types

The utility-types package provides a collection of utility types for TypeScript, similar to type-fest. It includes types for operations like picking, omitting, and readonly transformations. It is comparable to type-fest but may have a different set of utilities and slightly different implementations.

ts-essentials

ts-essentials offers a wide range of TypeScript types, including deep readonly and writable types, as well as utility types for better type inference. It is similar to type-fest in its goal to enhance TypeScript's type system but may differ in the specific types offered and its API design.

typesafe-actions

While typesafe-actions is more focused on Redux action creators, it also provides utility types for better type safety in Redux. It is similar to type-fest in that it enhances TypeScript's type system but is more specialized for Redux-related typing.

README

A collection of essential TypeScript types

---

Many of the types here should have been built-in.

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.

Install

$ npm install type-fest

Usage

import {Omit} from 'type-fest';

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

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

API

See the types file.

License

(MIT OR CC0-1.0)