如何将长度不同的两个数组的值相加？

function addArrays(arr1, arr2) {
    const n = arr1.length;
    const m = arr2.length;
  
    // 扩展数组长度
    if (n > m) {
        arr2 = arr2.concat(Array(n - m).fill(0));
    } else if (n < m) {
        arr1 = arr1.concat(Array(m - n).fill(0));
    }
  
    const result = [];
    let carry = 0;
  
    // 逐位相加
    for (let i = arr1.length - 1; i >= 0; i--) {
        const sum = arr1[i] + arr2[i] + carry;
        result.unshift(sum % 10);
        carry = Math.floor(sum / 10);
    }
  
    // 处理最后的进位
    if (carry > 0) {
        result.unshift(carry);
    }
  
    return result;
}

const arr1 = [1, 2, 3];
const arr2 = [9, 8, 7, 6];
const result = addArrays(arr1, arr2);
console.log(result);