findLast

The findLast() method returns the last element of an array that satisfies a given condition.

Interactive example

Syntax

Classic signature

// Type Guard
function findLast<
	GenericInput extends readonly unknown[],
	GenericOutput extends GenericInput[number]
>(
	input: GenericInput, 
	predicate: (
		element: GenericInput[number], 
		params: ArrayFindLastParams
	) => element is GenericOutput
): GenericOutput | undefined

// Boolean
function findLast<
	GenericInput extends readonly unknown[]
>(
	input: GenericInput, 
	predicate: (
		element: GenericInput[number], 
		params: ArrayFindLastParams
	) => boolean
): GenericInput[number] | undefined

Curried signature

// Type Guard
function findLast<
	GenericInput extends readonly unknown[],
	GenericOutput extends GenericInput[number]
>(
	predicate: (
		element: GenericInput[number], 
		params: ArrayFindLastParams
	) => element is GenericOutput
): (input: GenericInput) => GenericOutput | undefined

// Boolean
function findLast<
	GenericInput extends readonly unknown[]
>(
	predicate: (
		element: GenericInput[number], 
		params: ArrayFindLastParams
	) => boolean
): (input: GenericInput) => GenericInput[number] | undefined

Helper parameters

interface ArrayFindLastParams {
	index: number;
}

Parameters

• input: The array to search in.
• predicate: Predicate function that tests each element (and can act as a type guard). Receives the element and an object containing the index.
• params.index: Position of the current element in the array.

Return value

The last element that satisfies the condition, or undefined if no element matches.

See also

• find - Finds the first element that satisfies a condition
• findLastIndex - Returns the index instead of the element

Sources

• MDN Web Docs - Array.findLast()