useArrayFindLast()

Category

Array

Export Size

461 B

Gzipped

275 B

SSR

SSR support

Last updated: 24/04/2026

Overview

useArrayFindLast walks from the end of source and returns the first item (i.e. last in array order) that satisfies predicate, or undefined. The implementation uses a for loop (no dependency on Array.prototype.findLast), which helps in environments where that method is missing or you want the same behavior everywhere. It is still wrapped in useMemo([source, predicate]). Stabilize predicate.

What it accepts

1. source: T[]
2. predicate: same idea as find / findIndex

What it returns

• T | undefined

Usage

Get the last even number in a log of integers.

import { useCallback, useState } from 'react'
import useArrayFindLast from '@dedalik/use-react/useArrayFindLast'

function Example() {
  const [log, setLog] = useState([1, 2, 3, 4, 3, 6])
  const lastEven = useArrayFindLast(
    log,
    useCallback((n: number) => n % 2 === 0, []),
  )

  return (
    <div>
      <p>log: {log.join(', ')}</p>
      <p>last even: {lastEven ?? '-'}</p>
      <button type='button' onClick={() => setLog((L) => [...L, 8])}>
        push 8
      </button>
    </div>
  )
}

export default function Demo() {
  return <Example />
}

API Reference

useArrayFindLast

Signature: useArrayFindLast<T>(source: T[], predicate: (item: T, index: number, array: T[]) => boolean): T | undefined

Copy-paste hook

TypeScript

import { useMemo } from 'react'

/**
 * Memoized Array.findLast fallback-safe lookup.
 */
export default function useArrayFindLast<T>(
  source: T[],
  predicate: (item: T, index: number, array: T[]) => boolean,
): T | undefined {
  return useMemo(() => {
    for (let i = source.length - 1; i >= 0; i -= 1) {
      const item = source[i]
      if (predicate(item, i, source)) return item
    }
    return undefined
  }, [source, predicate])
}

JavaScript

import { useMemo } from 'react'

/**
 * Memoized Array.findLast fallback-safe lookup.
 */
export default function useArrayFindLast(source, predicate) {
  return useMemo(() => {
    for (let i = source.length - 1; i >= 0; i -= 1) {
      const item = source[i]
      if (predicate(item, i, source)) return item
    }
    return undefined
  }, [source, predicate])
}