Function transform

  • transform<T, S>(array, iteratee, accumulator?): S[]

  • An alternative to reduce this method transforms object to a new accumulator object which is the result of running each of its own enumerable string keyed properties thru iteratee, with each invocation potentially mutating the accumulator object. If accumulator is not provided, a new object with the same [[Prototype]] will be used. The iteratee is invoked with four arguments: (accumulator, value, key, object). Iteratee functions may exit iteration early by explicitly returning false.

    Type Parameters

    • T
    • S

    Parameters

    • array: T[]

      The object to iterate over.

    • iteratee: ((accumulator: S[], value: T, index: number, object: T[]) => boolean)

      The function invoked per iteration.

        • (accumulator, value, index, object): boolean

        • Parameters

          • accumulator: S[]
          • value: T
          • index: number
          • object: T[]

          Returns boolean

    • Optionalaccumulator: S[] = []

      The custom accumulator value.

    Returns S[]

    Returns the accumulated value.

    Since

    1.3.0

    See

    reduce, reduceRight

    Example

    transform([2, 3, 4], (result, n) => {
      result.push(n *= n)
      return n % 2 == 0
    }, [])
    // => [4, 9]

    transform({ 'a': 1, 'b': 2, 'c': 1 }, (result, value, key) => {
      (result[value] || (result[value] = [])).push(key)
    }, {})
    // => { '1': ['a', 'c'], '2': ['b'] }

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