获取嵌套对象长度

const nestedObject = {
  level1: {
    level2: {
      items: [1, 2, 3, 4]
    }
  }
};

const length = nestedObject.level1.level2.items.length;
console.log(length); // 输出：4

function getNestedArrayLength(obj, keyToFind) {
  for (let key in obj) {
    if (key === keyToFind && Array.isArray(obj[key])) {
      return obj[key].length;
    }
    if (typeof obj[key] === 'object') {
      const length = getNestedArrayLength(obj[key], keyToFind);
      if (length !== undefined) {
        return length;
      }
    }
  }
  return undefined;
}

const length = getNestedArrayLength(nestedObject, 'items');
console.log(length); // 输出：4