如何找到数组的中间索引？

function findMiddleIndex(nums) {
  let totalSum = 0;
  for (let i = 0; i < nums.length; i++) {
    totalSum += nums[i];
  }

  let leftSum = 0;
  for (let i = 0; i < nums.length; i++) {
    if (leftSum === totalSum - leftSum - nums[i]) {
      return i;
    }
    leftSum += nums[i];
  }

  return -1; // 没有找到中间索引
}

// 示例用法
const nums = [1, 2, 3, 4, 5, 6];
const middleIndex = findMiddleIndex(nums);
if (middleIndex !== -1) {
  console.log("数组的中间索引为：" + middleIndex);
} else {
  console.log("数组没有中间索引");
}