Function reversePortionOfArray

javascript/0189-rotate-array.js:19–25

(nums, start, end)

};

var reversePortionOfArray = function (nums, start, end) {
    while (start < end) {
        [nums[start], nums[end]] = [nums[end], nums[start]];
        start++;
        end--;
    }
};

/**
 * Two Pointers