如何在通过值搜索嵌套对象时找到完整的点分隔的键？

const obj = {
  a: {
    b: {
      c: 1,
      d: 2
    },
    e: {
      f: {
        g: 3
      }
    }
  },
  h: 4
};

function findKey(obj, targetValue) {
  for (let key in obj) {
    if (obj[key] === targetValue) {
      return key;
    }
    if (typeof obj[key] === 'object') {
      const nestedKey = findKey(obj[key], targetValue);
      if (nestedKey) {
        return key + '.' + nestedKey;
      }
    }
  }
  return null;
}

const targetKey = findKey(obj, 3);
console.log(targetKey); // 输出 'a.e.f.g'