Function swap

javascript/0041-first-missing-positive.js:45–46

(nums, index, indexKey)

    isPositive(num) && isInBound(num, nums) && !isEqual(num, indexNum);

const swap = (nums, index, indexKey) =>
    ([nums[index], nums[indexKey]] = [nums[indexKey], nums[index]]);

const isPositive = (num) => 0 < num;