对象常用方法

1.Object.keys()

遍历对象，取出对象中所有的键或值

const person = {
  name: "zhang",
  age: 18,
};
Object.keys(person).forEach((key) => {
  console.log(key); // name age
});

2. Object.values()

取出对象中所有的值

const person = {
  name: "zhang",
  age: 18,
};
console.log(Object.values(person)); // ['zhang',18]

3.Object.assign(target, …sources)

将所有sources中的属性，放到target中，追加没有的属性，替换已存在属性的值

const person = {
  name: "zhang",
  age: 18,
};
const res = Object.assign(
  person,
  { hobby: ["basketball"] },
  { a: 1 },
  { name: "wang" }
);

console.log(res, person); // {name: 'wang', age: 18, hobby: Array(1), a: 1}

4.Object.entries()

返回字符串键属性 [key, value] 对的数组

const person = {
  name: "zhang",
  age: 18,
};

for (const [key, value] of Object.entries(person)) {
  console.log(key, value); // name zhang // age 18
}

5.Object.is()

加强版意义上的===
举几个临界值

Object.is(NaN, NaN), // true
Object.is(+0, -0), //false
Object.is(3, "3") // false

6.Object.freeze()

冻结对象，只允许读取，允许修改，只作用于一层

const person = {
  name: "zhang",
  age: 18,
  firends: [
    {
      name: "li",
      age: 20,
    },
  ],
};
Object.freeze(person);
person.firends[0].name = "wang";
console.log(person); // firends[0].name = wang

7.Object.seal()

密封对象，只允许修改，不允许删除、增加，作用于最外层

const person = {
  name: "zhang",
  age: 18,
};
Object.seal(person);
person.firends = [
  {
    name: "li",
    age: 20,
  },
];

console.log(person); // {name: 'zhang', age: 18}

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