Binary-Swap.js

/*
  Task
  Write a function binarySwap which accepts exactly 1 argument and should behave as follows:

  Basic Behaviour
  If the input is 0 then the return value should be 1 e.g. binarySwap(0) === 1
  If the input is 1 then the return value should be 0 e.g. binarySwap(1) === 0
  The strings '0' and '1' should be treated as 0 and 1 respectively e.g. binarySwap('0') === 1 && binarySwap('1') === 0
  Functions
    When the argument is a function, binarySwap should obtain its return value and operate on it.
    If the return value is still a function, your function is expected to obtain the return values
    of the nested functions until the return value is no longer a function. E.g.

    binarySwap(function () {
      return 0;
    }) --> binarySwap(0) === 1

    binarySwap(function () {
      return function () {
        return 1;
      }
    }) --> binarySwap(function () {
      return 1;
    }) --> binarySwap(1) === 0

    binarySwap(function () {
      return function () {
        return function () {
          return function () {
            return '0';
          }
        }
      }
    }) --> binarySwap(function () {
      return function () {
        return function () {
          return '0';
        }
      }
    }) --> binarySwap(function () {
      return function () {
        return '0';
      }
    }) --> binarySwap(function () {
      return '0';
    }) --> binarySwap('0') === 1

    binarySwap(function () {
      return function () {
        return [0, '1'];
      }
    }) --> binarySwap(function () {
      return [0, '1'];
    }) === binarySwap([0, '1'])
  Arrays
    When given an array, your function should apply the binary swap to each element in the array
    and return the resulting array except if the array contains exactly one element and that element
    is not a function - in that case simply treat the array as a number. E.g.

    binarySwap([0]) === 1 // Note: for arrays with exactly one element, simply return the number, NOT the array
    binarySwap([1, 0]) <--> [0, 1]
    binarySwap(['1', 0, '0', 1]) <--> [0, 1, 1, 0]
  Your function should also deal with nested arrays properly:

  binarySwap([1, [0, ['1', ['0', [1]]]]]) <--> [0, [1, [0, [1, 0]]]]
*/

// Answer:

function binarySwap(input) {
  switch (typeof input) {
      case 'number':
      case 'string':
        input = Number(input);
        return input === 0 ? 1 : 0;
      case 'function':
        return binarySwap(input())
      case 'object':
        if (input.length < 2) return binarySwap(input[0])
        else return input.map(element => binarySwap(element))
      default:
        throw new Error('incorrect input')
  }
}

// BigO: O(n)