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
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
-
Primitive
- Matches any primitive value. -
Class
- Matches aclass
constructor. -
TypedArray
- Matches any typed array, likeUint8Array
orFloat64Array
. -
JsonObject
- Matches a JSON object. -
JsonArray
- Matches a JSON array. -
JsonValue
- Matches any valid JSON value. -
ObservableLike
- Matches a value that is like an Observable.
Utilities
-
Omit
- Create a type from an object type without certain keys. -
Mutable
- Convert an object withreadonly
properties into a mutable object. Inverse ofReadonly<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. -
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.
Miscellaneous
-
PackageJson
- Type for npm'spackage.json
file.
Declined types
If we decline a type addition, we will make sure to document the better solution here.
Tips
Built-in types
There are many advanced types most users don't know about.
-
Partial<T>
- Make all properties inT
optional. -
Required<T>
- Make all properties inT
required. -
Readonly<T>
- Make all properties inT
readonly. -
Pick<T, K>
- FromT
, pick a set of properties whose keys are in the unionK
. -
Record<K, T>
- Construct a type with a set of propertiesK
of typeT
. -
Exclude<T, U>
- Exclude fromT
those types that are assignable toU
. -
Extract<T, U>
- Extract fromT
those types that are assignable toU
. -
NonNullable<T>
- Excludenull
andundefined
fromT
. -
Parameters<T>
- Obtain the parameters of a function type in a tuple. -
ConstructorParameters<T>
- Obtain the parameters of a constructor function type in a tuple. -
ReturnType<T>
– Obtain the return type of a function type. -
InstanceType<T>
– Obtain the instance type of a constructor function type.
You can find some examples in the TypeScript docs.
Maintainers
License
(MIT OR CC0-1.0)