\n \n \n\n[](https://travis-ci.com/sindresorhus/type-fest)\n[](https://www.youtube.com/watch?v=9auOCbH5Ns4)\n\n\nMany 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/master/CONTRIBUTING.md).\n\nEither add this package as a dependency or copy-paste the needed types. No credit required. 👌\n\nPR welcome for additional commonly needed types and docs improvements. Read the [contributing guidelines](.github/contributing.md) first.\n\n\n## Install\n\n```\n$ npm install type-fest\n```\n\n\n## Usage\n\n```ts\nimport {Omit} from 'type-fest';\n\ntype Foo = {\n\tunicorn: string;\n\trainbow: boolean;\n};\n\ntype FooWithoutRainbow = Omit;\n//=> {unicorn: string}\n```\n\n\n## API\n\nSee the [types file](index.d.ts) for complete docs.\n\n### Basic\n\n- `Primitive` - Matches any [primitive value](https://developer.mozilla.org/en-US/docs/Glossary/Primitive).\n- `Class` - Matches a [`class` constructor](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Classes).\n- `TypedArray` - Matches any [typed array](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray), like `Uint8Array` or `Float64Array`.\n- `JsonObject` - Matches a JSON object.\n- `JsonArray` - Matches a JSON array.\n- `JsonValue` - Matches any valid JSON value.\n- `ObservableLike` - Matches a value that is like an [Observable](https://github.com/tc39/proposal-observable).\n\n### Utilities\n\n- `Omit` - Create a type from an object type without certain keys.\n- `Merge` - Merge two types into a new type. Keys of the second type overrides keys of the first type.\n- `MergeExclusive` - Create a type that has mutually exclusive properties.\n- `RequireAtLeastOne` - Create a type that requires at least one of the given properties.\n- `LiteralUnion` - Allows creating 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](https://github.com/Microsoft/TypeScript/issues/29729).\n\n### Miscellaneous\n\n- `PackageJson` - Type for [npm's `package.json` file](https://docs.npmjs.com/creating-a-package-json-file).\n\n\n## Declined types\n\n*If we decline a type addition, we will make sure to document the better solution here.*\n\n\n## Tips\n\n### Built-in types\n\nThere are many advanced types most users don't know about.\n\n- [`Partial`](https://github.com/Microsoft/TypeScript/blob/2961bc3fc0ea1117d4e53bc8e97fa76119bc33e3/src/lib/es5.d.ts#L1401-L1406) - Make all properties in `T` optional.\n- [`Required`](https://github.com/Microsoft/TypeScript/blob/2961bc3fc0ea1117d4e53bc8e97fa76119bc33e3/src/lib/es5.d.ts#L1408-L1413) - Make all properties in `T` required.\n- [`Readonly`](https://github.com/Microsoft/TypeScript/blob/2961bc3fc0ea1117d4e53bc8e97fa76119bc33e3/src/lib/es5.d.ts#L1415-L1420) - Make all properties in `T` readonly.\n- [`Pick`](https://github.com/Microsoft/TypeScript/blob/2961bc3fc0ea1117d4e53bc8e97fa76119bc33e3/src/lib/es5.d.ts#L1422-L1427) - From `T`, pick a set of properties whose keys are in the union `K`.\n- [`Record`](https://github.com/Microsoft/TypeScript/blob/2961bc3fc0ea1117d4e53bc8e97fa76119bc33e3/src/lib/es5.d.ts#L1429-L1434) - Construct a type with a set of properties `K` of type `T`.\n- [`Exclude`](https://github.com/Microsoft/TypeScript/blob/2961bc3fc0ea1117d4e53bc8e97fa76119bc33e3/src/lib/es5.d.ts#L1436-L1439) - Exclude from `T` those types that are assignable to `U`.\n- [`Extract`](https://github.com/Microsoft/TypeScript/blob/2961bc3fc0ea1117d4e53bc8e97fa76119bc33e3/src/lib/es5.d.ts#L1441-L1444) - Extract from `T` those types that are assignable to `U`.\n- [`NonNullable`](https://github.com/Microsoft/TypeScript/blob/2961bc3fc0ea1117d4e53bc8e97fa76119bc33e3/src/lib/es5.d.ts#L1446-L1449) - Exclude `null` and `undefined` from `T`.\n- [`Parameters`](https://github.com/Microsoft/TypeScript/blob/2961bc3fc0ea1117d4e53bc8e97fa76119bc33e3/src/lib/es5.d.ts#L1451-L1454) - Obtain the parameters of a function type in a tuple.\n- [`ConstructorParameters`](https://github.com/Microsoft/TypeScript/blob/2961bc3fc0ea1117d4e53bc8e97fa76119bc33e3/src/lib/es5.d.ts#L1456-L1459) - Obtain the parameters of a constructor function type in a tuple.\n- [`ReturnType`](https://github.com/Microsoft/TypeScript/blob/2961bc3fc0ea1117d4e53bc8e97fa76119bc33e3/src/lib/es5.d.ts#L1461-L1464) – Obtain the return type of a function type.\n- [`InstanceType`](https://github.com/Microsoft/TypeScript/blob/2961bc3fc0ea1117d4e53bc8e97fa76119bc33e3/src/lib/es5.d.ts#L1466-L1469) – Obtain the instance type of a constructor function type.\n\nYou can find some examples in the [TypeScript docs](https://www.typescriptlang.org/docs/handbook/advanced-types.html#predefined-conditional-types).\n\n\n## Maintainers\n\n- [Sindre Sorhus](https://github.com/sindresorhus)\n- [Jarek Radosz](https://github.com/CvX)\n- [Dimitri Benin](https://github.com/BendingBender)\n\n\n## License\n\n(MIT OR CC0-1.0)\n",
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