countIn (method)

Abstract countIn

• countIn<U>(this, f): Opt<number>

• Counts the number of elements in the array inside the Opt that satisfy the predicate.

  Type Parameters

  • U

  Parameters

  • this: Opt<U[]>

  • f: ((x) => boolean)

    The predicate function to test each element.

    • • (x): boolean

      • Parameters

        • x: U

        Returns boolean

  Returns Opt<number>

  An Opt containing the count of elements that satisfy the predicate, or None if the Opt is None.

  Example

  opt([1, 2, 3]).countIn(x => x > 1) // Some(2)
  opt([]).countIn(x => x > 1) // Some(0)
  none.countIn(x => x > 1) // None