es-toolkit/dist/array/flatMapDeep.d.ts

A state-of-the-art, high-performance JavaScript utility library with a small bundle size and strong type annotations.

import { ExtractNestedArrayType } from './flattenDeep.js';

/**
 * Recursively maps each element in an array using a provided iteratee function and then deeply flattens the resulting array.
 *
 * @template T - The type of elements within the array.
 * @template U - The type of elements within the returned array from the iteratee function.
 * @param {T[]} arr - The array to flatten.
 * @param {(item: T, index: number, array: readonly T[]) => U} iteratee - The function that produces the new array elements. It receives the element, its index, and the array.
 * @returns {Array<ExtractNestedArrayType<U>>} A new array that has been flattened.
 *
 * @example
 * const result = flatMapDeep([1, 2, 3], n => [[n, n]]);
 * // [1, 1, 2, 2, 3, 3]
 */
declare function flatMapDeep<T, U>(arr: readonly T[], iteratee: (item: T, index: number, array: readonly T[]) => U): Array<ExtractNestedArrayType<U>>;

export { flatMapDeep };