Type Alias ReadonlyTuple<Element, Length>

ReadonlyTuple: number extends Length
? readonly Element[]
: BuildTupleHelper<Element, Length, []>

Create a type that represents a read-only tuple of the given type and length.

Use-cases:

Declaring fixed-length tuples with a large number of items.
Creating a range union (for example, 0 | 1 | 2 | 3 | 4 from the keys of such a type) without having to resort to recursive types.
Creating a tuple of coordinates with a static length, for example, length of 3 for a 3D vector.

Type Parameters

Element
Length extends number

Example

import {ReadonlyTuple} from 'type-fest';

type FencingTeam = ReadonlyTuple<string, 3>;

const guestFencingTeam: FencingTeam = ['Josh', 'Michael', 'Robert'];

const homeFencingTeam: FencingTeam = ['George', 'John'];
//=> error TS2322: Type string[] is not assignable to type 'FencingTeam'

guestFencingTeam.push('Sam');
//=> error TS2339: Property 'push' does not exist on type 'FencingTeam'