Function flatMap

  • flatMap<T, R = any>(collection: T[], iteratee?: ArrayIteratee<T, T[]>): R[]

  • Creates a flattened array of values by running each element in collection thru iteratee and flattening the mapped results. The iteratee is invoked with three arguments: (value, index|key, collection).

    Type Parameters

    • T
    • R = any

    Parameters

    • collection: T[]

      The collection to iterate over.

    • Optionaliteratee: ArrayIteratee<T, T[]>

      The function invoked per iteration.

    Returns R[]

    Returns the new flattened array.

    Since

    5.4.0

    See

    [[flatMapDeep]],[[flatMapDepth]],[[flatten]],[[flattenDeep]],[[flattenDepth]],[[map]],[[mapKeys]],[[mapValues]]

    Example

    function duplicate(n) {
      return [n, n]
    }

    flatMap([1, 2], duplicate)
    // => [1, 1, 2, 2]
  • flatMap<T, R = any>(
        collection: Record<string, T>,
        iteratee?: RecordIteratee<T, Record<string, T>>,
    ): R[]

  • Creates a flattened array of values by running each element in collection thru iteratee and flattening the mapped results. The iteratee is invoked with three arguments: (value, index|key, collection).

    Type Parameters

    • T
    • R = any

    Parameters

    • collection: Record<string, T>

      The collection to iterate over.

    • Optionaliteratee: RecordIteratee<T, Record<string, T>>

      The function invoked per iteration.

    Returns R[]

    Returns the new flattened array.

    Since

    5.4.0

    See

    [[flatMapDeep]],[[flatMapDepth]],[[flatten]],[[flattenDeep]],[[flattenDepth]],[[map]],[[mapKeys]],[[mapValues]]

    Example

    function duplicate(n) {
      return [n, n]
    }

    flatMap([1, 2], duplicate)
    // => [1, 1, 2, 2]

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