对象

1. 创建对象

// 字面量创建（推荐）
const person = {
    name: "张三",
    age: 25,
    city: "北京",
    sayHello: function () {
        console.log(`你好，我是${this.name}`);
    },
};

// 构造函数创建
function Person(name, age) {
    this.name = name;
    this.age = age;
    this.greet = function () {
        console.log(`Hi, I'm ${this.name}`);
    };
}

const person1 = new Person("李四", 30);

// 使用 Object.create()
const personProto = {
    greet() {
        console.log(`Hello, ${this.name}`);
    },
};

const person2 = Object.create(personProto);
person2.name = "王五";

2. 访问和修改属性

const user = {
    name: "小明",
    age: 20,
};

// 访问属性
console.log(user.name); // 点表示法
console.log(user["age"]); // 括号表示法

// 修改属性
user.name = "小红";
user["age"] = 21;

// 添加新属性
user.email = "xiaohong@example.com";
user["phone"] = "13800138000";

// 删除属性
delete user.phone;

3. 对象方法

const calculator = {
    num1: 0,
    num2: 0,

    // 方法定义
    setNumbers: function (a, b) {
        this.num1 = a;
        this.num2 = b;
    },

    // ES6简写方法
    add() {
        return this.num1 + this.num2;
    },

    subtract() {
        return this.num1 - this.num2;
    },
};

calculator.setNumbers(10, 5);
console.log(calculator.add()); // 15
console.log(calculator.subtract()); // 5

4. 遍历对象

const student = {
    name: "张三",
    age: 20,
    grade: "A",
    school: "清华大学",
};

// for...in 循环
for (let key in student) {
    console.log(`${key}: ${student[key]}`);
}

// Object.keys()
const keys = Object.keys(student);
console.log(keys); // ['name', 'age', 'grade', 'school']

// Object.values()
const values = Object.values(student);
console.log(values); // ['张三', 20, 'A', '清华大学']

// Object.entries()
const entries = Object.entries(student);
entries.forEach(([key, value]) => {
    console.log(`${key}: ${value}`);
});

5. 对象解构

const product = {
    id: 1,
    name: "手机",
    price: 2999,
    category: "电子产品",
};

// 基本解构
const { name, price } = product;
console.log(name, price); // 手机 2999

// 重命名
const { name: productName, price: productPrice } = product;

// 默认值
const { warranty = "1年" } = product;

// 嵌套解构
const company = {
    name: "ABC公司",
    address: {
        city: "上海",
        street: "南京路",
    },
};

const {
    name: companyName,
    address: { city },
} = company;

6. 对象合并和克隆

const obj1 = { a: 1, b: 2 };
const obj2 = { b: 3, c: 4 };

// 合并对象（浅合并）
const merged = Object.assign({}, obj1, obj2);
// 或使用扩展运算符
const merged2 = { ...obj1, ...obj2 };

// 深度克隆（简单方式，不处理函数和特殊对象）
const shallowClone = { ...obj1 };
const deepClone = JSON.parse(JSON.stringify(obj1)); // 注意：会丢失函数和undefined

7. 计算属性名