1. function swap(i, j) {
    2.     let temp = i;
    3.     i = j;
    4.     j = temp;
    5. }
    7. function reverse(str, start, end) {
    8.     let offset = (end - start + 1) / 2;
    9.     for (let i = start, j = end; i < start + offset; i++, j--) {
    10.         swap(str[i], str[j]);
    11.     }
    12. }
    15. function reverseStr(s, k) {
    16.     for (let i = 0; i < s.length; i += 2 * k) {
    17.         if (i + k <= s.length) {
    18.             reverse(s, i, i + k - 1);
    19.             continue;
    20.         }
    22.         reverse(s, i, s.size - 1);
    23.     }
    24. }