你應該簡單地將 i < A.length && j < B.length 作為循環條件進行檢查。

這是你更新後的程式碼：

const mergeSort = {
  solve: function (A) {
    return this.mergeSortFunction(A);
  },
  mergeTwoSortedArrays: function (A, B) {
    let i = 0;
    let j = 0;
    let k = 0;
    let C = [];
    while (i < A.length && j < B.length) {
      if (A[i] < B[j]) {
        C[k] = A[i];
        i++;
        k++;
      } else {
        C[k] = B[j];
        j++;
        k++;
      }
    }
    while (j < B.length) {
      C[k] = B[j];
      k++;
      j++;
    }
    while (i < A.length) {
      C[k] = A[i];
      k++;
      i++;
    }
    return C;
  },
  mergeSortFunction: function (a) {
    let n = a.length;
    if (n <= 1) return a;
    let c = Array.from({ length: Math.floor(n / 2) }, (_, i) => a[i]);
    let d = Array.from({ length: n - c.length }, (_, i) => a[c.length + i]);
    return this.mergeTwoSortedArrays(this.mergeSortFunction(c), this.mergeSortFunction(d));
  }
};

// 示例
const inputArray = [38, 27, 43, 3, 9, 82, 10];
const sortedArray = mergeSort.solve(inputArray);
console.log(sortedArray); 
// 输出：[3, 9, 10, 27, 38, 43, 82]