flattenDeepThenMap

Flattens all depths of a nested array and then maps each element using the provided iteratee function.

Behaves the same as arr.flat(Infinity).map(iteratee) while improving type issues.

Code

🔗 View source code

Benchmark

• hz: Operations per second
• mean: Average response time (ms)

Name	hz	mean	Performance
modern-kit/flattenDeepThenMap	1,587,624.53	0.0004	fastest
lodash/flattenDeep.map	1,222,383.95	0.0006	-
js built-in/flat(Infinity).map	330,750.78	0.0029	slowest

• modern-kit/flattenDeepThenMap
  • 1.30x faster than lodash/flattenDeep.map
  • 4.80x faster than js built-in/flat(Infinity).map

Interface

typescript

/**
 * @description A utility type that recursively unwraps nested array types to extract the innermost element type
 */
type ExtractNestedArrayType<T> = T extends readonly (infer U)[]
  ? ExtractNestedArrayType<U>
  : T;

typescript

function flattenDeepThenMap<T, U>(
  arr: T[] | readonly T[],
  iteratee: (item: ExtractNestedArrayType<T>) => U
): U[];

Usage

typescript

import { flattenDeepThenMap } from '@modern-kit/utils';

const arr = [1, 2, [3, 4, [5, 6]]];
flattenDeepThenMap(arr, (item) => ({ id: item }));
// [{ id: 1}, { id: 2}, { id: 3}, { id: 4}, { id: 5}, { id: 6}];