如何有效地将由两个数组表示的两个整数相加，将解放入另一个数组中

function addArrays(num1, num2) {
  const result = [];
  let carry = 0;
  let i = num1.length - 1;
  let j = num2.length - 1;

  while (i >= 0 || j >= 0) {
    const digit1 = i >= 0 ? num1[i] : 0;
    const digit2 = j >= 0 ? num2[j] : 0;
    const sum = digit1 + digit2 + carry;

    result.push(sum % 10);
    carry = Math.floor(sum / 10);

    i--;
    j--;
  }

  if (carry !== 0) {
    result.push(carry);
  }

  return result.reverse();
}

// 示例用法
const num1 = [1, 2, 3];
const num2 = [4, 5, 6];
const sum = addArrays(num1, num2);
console.log(sum); // 输出 [5, 7, 9]