如何检查对象的键值是否为空？

function checkObjectKeyValue(obj) {
  if (obj === null || obj === undefined) {
    console.log("对象为空");
    return;
  }

  const keys = Object.keys(obj);
  if (keys.length === 0) {
    console.log("对象的键值为空");
    return;
  }

  for (const key of keys) {
    const value = obj[key];
    if (value === null || value === undefined || value === "") {
      console.log(`键 ${key} 的值为空`);
    }
  }
}

// 示例用法
const obj1 = { name: "John", age: 30, email: "" };
checkObjectKeyValue(obj1);

const obj2 = null;
checkObjectKeyValue(obj2);

const obj3 = { };
checkObjectKeyValue(obj3);