JavaScript ... 扩展符是深拷贝还是浅拷贝

** 先说结论，JavaScript的...既是深拷贝也是浅拷贝。**

深拷贝

简单的对象，进行...扩展就是深拷贝。

let student = {
  name: "张三",
  age: "20",
};

let _student = { ...student };
_student.name = "李四";
console.log({ student, _student });

{
  student: { name: '张三', age: '20' },
  _student: { name: '李四', age: '20' }
}

浅拷贝

复杂的对象，进行...扩展就是浅拷贝。假设说我在上面的 Student 对象里面又加了一层。

let student = {
  name: "张三",
  age: "20",
  area: {
    province: "广东省",
    city: "深圳市",
  },
};

{
  student: { name: '张三', age: '20', area: { province: '山东省', city: '聊城市' } },
  _student: { name: '张三', age: '20', area: { province: '山东省', city: '聊城市' } }
}