IsTuple

Since 1.0.0

Check if a type is a tuple.

Signature

type IsTuple<T> = T extends readonly [unknown, ...unknown[]]
  ? T extends readonly unknown[]
    ? number extends T['length']
      ? false
      : true
    : false
  : false

Parameters

Parameter	Description
T	The type to check

Returns

Returns true if T is a tuple type (fixed-length array), false otherwise.

Examples

Basic Usage

import type { IsTuple } from 'uni-types'

type Check1 = IsTuple<[string, number]> // true
type Check2 = IsTuple<[string]> // true
type Check3 = IsTuple<readonly [number, string]> // true
type Check4 = IsTuple<[]> // true (empty tuple)

Non-Tuple Types

type Check5 = IsTuple<string[]> // false
type Check6 = IsTuple<number[]> // false
type Check7 = IsTuple<string> // false

Usage in Conditional Types

import type { IsTuple } from 'uni-types'

type GetLength<T> = IsTuple<T> extends true 
  ? T extends readonly unknown[] ? T['length'] : never 
  : number

type Len1 = GetLength<[1, 2, 3]> // 3
type Len2 = GetLength<string[]> // number

Related

• IsArray - Check if type is an array
• TupleLength - Get tuple length