For AI agents: the complete documentation index is available at /llms.txt, the full documentation bundle is available at /llms-full.txt, and this page is available as Markdown at /reference/fp/flattenDeep.md.
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    flattenDeep (Functional Programming) es-toolkit

    Creates a function that recursively flattens nested arrays. Use it with pipe.

    const result = pipe(array, flattenDeep());
    Info

    Prefer the original es-toolkit flattenDeep in ordinary code. Use this fp variant when composing transformations with pipe.

    Usage

    flattenDeep recursively removes every nested array layer from the piped array. It is lazy-capable inside pipe.

    import { flattenDeep, pipe } from 'es-toolkit/fp';

pipe([1, [2, [3, [4]]]], flattenDeep()); // => [1, 2, 3, 4]

    Parameters

    This function takes no arguments; call it as flattenDeep().

    Returns

    A function that maps a nested array to a deeply flattened array.

    (array: readonly T[]) => Array<ExtractNestedArrayType<T>>
    Source: es-toolkit

    Re-exported verbatim from es-toolkit. Implementation, edge cases, and performance behavior are owned upstream. This page mirrors the documentation at the pinned version; the linked source is authoritative.