A collection of essential TypeScript types. 

A collection of essential TypeScript types

sindresorhus

type-fest

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{{count, number}} commits last two months

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{{count, number}} version published in last two months

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	"description": "A collection of essential TypeScript types",

	"funding": "https://github.com/sponsors/sindresorhus",

		"test": "xo && tsd && tsc && node script/test/source-files-extension.js"

			"@typescript-eslint/ban-ts-comment": "off",

			"@typescript-eslint/ban-types": "off",

			"@typescript-eslint/naming-convention": "off",

			"@typescript-eslint/no-redeclare": "off",

			"@typescript-eslint/no-confusing-void-expression": "off"

A collection of essential TypeScript types

<a href="https://github.com/sponsors/sindresorhus">Sindre Sorhus' open source work is supported by the community</a>

Start selling to enterprise customers with just a few lines of code.

Add Single Sign-On (and more) in minutes instead of months.

Paperwork that makes the data work.

					Easy APIs for paperwork. PDF generation, e-signature and embeddable no-code webforms.

					The easiest way to build paperwork automation into your product.

[![](https://img.shields.io/badge/unicorn-approved-ff69b4.svg)](https://giphy.com/gifs/illustration-rainbow-unicorn-26AHG5KGFxSkUWw1i)

[![npm dependents](https://badgen.net/npm/dependents/type-fest)](https://www.npmjs.com/package/type-fest?activeTab=dependents)

[![npm downloads](https://badgen.net/npm/dt/type-fest)](https://www.npmjs.com/package/type-fest)

[![Docs](https://paka.dev/badges/v0/cute.svg)](https://paka.dev/npm/type-fest)

Many of the types here should have been built-in. You can help by suggesting some of them to the [TypeScript project](https://github.com/Microsoft/TypeScript/blob/main/CONTRIBUTING.md).

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](.github/contributing.md) first.

**Help wanted with reviewing [proposals](https://github.com/sindresorhus/type-fest/issues) and [pull requests](https://github.com/sindresorhus/type-fest/pulls).**

- `Mutable`- See [`Writable`](https://github.com/sindresorhus/type-fest/blob/main/source/writable.d.ts)

- `Prettify`- See [`Simplify`](https://github.com/sindresorhus/type-fest/blob/main/source/simplify.d.ts)

- [`PackageJson`](source/package-json.d.ts) - There are a lot of tools that place extra configurations inside the `package.json` file. You can extend `PackageJson` to support these additional configurations.

	[Playground](https://www.typescriptlang.org/play?#code/JYWwDg9gTgLgBDAnmApnA3gBQIYGMDW2A5igFIDOEAdnNuXAEJ0o4HFmVUC+cAZlBBBwA5ElQBaXinIxhAbgCwAKFCRYCZGnQAZYFRgooPfoJHSANntmKlysWlaESFanAC8jZo-YuaAMgwLKwBhal5gIgB+AC44XX1DADpQqnCiLhsgA)

	import type {PackageJson as BasePackageJson} from 'type-fest';

	type PackageJson = BasePackageJson & {eslintConfig?: Linter.Config};

- [typed-query-selector](https://github.com/g-plane/typed-query-selector) - Enhances `document.querySelector` and `document.querySelectorAll` with a template literal type that matches element types returned from an HTML element query selector.

- [`Linter.Config`](https://github.com/DefinitelyTyped/DefinitelyTyped/blob/master/types/eslint/index.d.ts) - Definitions for the [ESLint configuration schema](https://eslint.org/docs/user-guide/configuring/language-options).

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

- [`Partial<T>`](https://www.typescriptlang.org/docs/handbook/utility-types.html#partialtype) - Make all properties in `T` optional.

	[Playground](https://www.typescriptlang.org/play/#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)

private updateConfig<Key extends keyof NodeConfig>(key: Key, value: NodeConfig[Key]) {

					type NodeConfigKey = keyof NodeConfig;

					for (const key of Object.keys(config) as NodeConfigKey[]) {

							this.updateConfig(key, updateValue);

// `Partial<NodeConfig>`` allows us to provide only a part of the

	new NodeAppBuilder().config({appName: 'ToDoApp'});

- [`Required<T>`](https://www.typescriptlang.org/docs/handbook/utility-types.html#requiredtype) - Make all properties in `T` required.

	[Playground](https://typescript-play.js.org/?target=6#code/AQ4SwOwFwUwJwGYEMDGNgGED21VQGJZwC2wA3gFCjXAzFJgA2A-AFzADOUckA5gNxUaIYjA4ckvGG07c+g6gF8KQkAgCuEFFDA5O6gEbEwUbLm2ESwABQIixACJIoSdgCUYAR3Vg4MACYAPGYuFvYAfACU5Ko0APRxwADKMBD+wFAAFuh2Vv7OSBlYGdmc8ABu8LHKsRyGxqY4oQT21pTCIHQMjOwA5DAAHgACxAAOjDAAdChYxL0ANLHUouKSMH0AEmAAhJhY6ozpAJ77GTCMjMCiV0ToSAb7UJPPC9WRgrEJwAAqR6MwSRQPFGUFocDgRHYxnEfGAowh-zgUCOwF6KwkUl6tXqJhCeEsxDaS1AXSYfUGI3GUxmc0WSneQA)

function submitContactForm(formData: Required<ContactForm>) {

			message: 'Hi! Could you tell me more about…',

	// TypeScript error: missing property 'message'

import type {OmitIndexSignature} from './omit-index-signature';

import type {PickIndexSignature} from './pick-index-signature';

import type {EnforceOptional} from './enforce-optional';

// Merges two objects without worrying about index signatures or optional keys.

// Merges two objects without worrying about index signatures.

type SimpleMerge<Destination, Source> = {

	[Key in keyof Destination | keyof Source]: Key extends keyof Source

	[Key in keyof Destination as Key extends keyof Source ? never : Key]: Destination[Key];

Merge two types into a new type. Keys of the second type overrides keys of the first type.

export type Merge<Destination, Source> = EnforceOptional<

SimpleMerge<PickIndexSignature<Destination>, PickIndexSignature<Source>>

& SimpleMerge<OmitIndexSignature<Destination>, OmitIndexSignature<Source>>>;

		{
		"name": "type-fest",
		"version": "3.7.1",
		"version": "3.7.2",
		"description": "A collection of essential TypeScript types",
		@@ -5,0 +5,0 @@ "license": "(MIT OR CC0-1.0)",

		@@ -5,10 +5,6 @@ import type {OmitIndexSignature} from './omit-index-signature';

		// Merges two objects without worrying about index signatures or optional keys.
		// Merges two objects without worrying about index signatures.
		type SimpleMerge<Destination, Source> = {
		[Key in keyof Destination \| keyof Source]: Key extends keyof Source
		? Source[Key]
		: Key extends keyof Destination
		? Destination[Key]
		: never;
		};
		[Key in keyof Destination as Key extends keyof Source ? never : Key]: Destination[Key];
		} & Source;

		@@ -15,0 +11,0 @@ /**

Improved metrics

Worsened metrics

		@@ -273,2 +273,3 @@ <div align="center">
		- `Mutable`- See [`Writable`](https://github.com/sindresorhus/type-fest/blob/main/source/writable.d.ts)
		- `Prettify`- See [`Simplify`](https://github.com/sindresorhus/type-fest/blob/main/source/simplify.d.ts)

		@@ -275,0 +276,0 @@ ## Tips