mapTuple

The mapTuple() method maps each element of an array while preserving tuple length at the type level.

Interactive example

Syntax

Classic signature

function mapTuple<
	GenericInput extends readonly unknown[],
	GenericOutput extends unknown
>(
	input: GenericInput,
	theFunction: (
		element: GenericInput[number],
		params: ArrayMapTupleParams<GenericInput>
	) => GenericOutput
): MapTuple<GenericInput, GenericOutput>

Curried signature

function mapTuple<
	GenericInput extends readonly unknown[],
	GenericOutput extends unknown
>(
	theFunction: (
		element: GenericInput[number],
		params: ArrayMapTupleParams<GenericInput>
	) => GenericOutput
): (input: GenericInput) => MapTuple<GenericInput, GenericOutput>

Helper parameters

interface ArrayMapTupleParams<
	GenericInputTuple extends readonly unknown[]
> {
	index: number;
	self: GenericInputTuple;
}

Parameters

• input: Array or tuple to transform.
• theFunction: Mapping function receiving current element, index, and source array.

Return value

A new mapped array. If input is a tuple, the output keeps the same tuple length.

See also

• map - Maps values in a generic array
• filter - Filters values based on a predicate

Sources

• MDN Web Docs - Array.prototype.map()