ES6 对象扩展

    //ES5 对象
    const getInfo=(id=1)=>{
        ajax...
        
        const name="cyy";
        const age=18;

        return {
            name:name,age:age,say:function(){
                console.log(this.name+this.age);
            }
        }
    }
    const cyy=getInfo();

    ES6 对象的简洁表示法
    const getInfo2=(id=1)=> {
            name,会去找同名变量
            age,say(){方法可以省略冒号
                console.log(.age);
            }
        }
    }
    const cyy2=getInfo2();    

const cyy={
    name:"cyy",age:18
}

ES6
const key="#^";
const cyy2={
    name:"cyy2"
}

ES6
const cyy2=
}

ES6
const key="str"
}

复制对象
const obj1={
    a:1
}
let cobj1={...obj1};

扩展运算符拷贝，拷贝的是引用地址
const obj1=22
    }
}
let cobj1={...obj1};
console.log(cobj1.c.d);11
cobj1.c.d=111;
console.log(cobj1.c.d);111
console.log(obj1.c.d);111

合并对象，属性相同时后面的会覆盖前面的
const obj1=
    }
}

const obj2={
    a:3
}

const nobj={
    ...obj1,...obj2
}

合并对象
const obj1=浅拷贝
nobj.c.d=111;
console.log(obj1.c.d);

console.log(+0===-0);true
console.log(Object.is(+0,-0));false

console.log(NaN==NaN);false
console.log(Object.is(NaN,NaN));true

对象合并，相同属性后面的覆盖前面的
let obj=Object.assign({a:1},{b:2,c:3},{c:4});{a: 1,b: 2,c: 4}
console.log(obj);

let obj1=22
    }
}
let obj2={
    c:3
}
let obj3=Object.assign({},obj1,obj2);
console.log(obj3);
//浅拷贝
obj3.b.b1=111;
console.log(obj1.b.b1);111

let obj=
    }
}

获取对象的属性名组成的数值
console.log(Object.keys(obj));["a","b"]获取对象的属性值组成的数值
console.log(Object.values(obj));[1,{…}]获取对象的属性名和属性值作为键值对，组成的数值
console.log(Object.entries(obj));[Array(2),Array(2)]

let obj=for of 遍历得到每一个属性名
for(let key of Object.keys(obj)){
    console.log(key);
}

for of 遍历，结构赋值得到每一个属性名和属性值
(let [k,v] of Object.entries(obj)){
    console.log(k,v);
}

let obj1={a:1};
let obj2={b:2};
obj2.__proto__=obj1;
let obj3={...obj2};

const obj={a:1};

const obj1={a:1};
const obj2={b:2};
const obj=Object.create(obj1);以obj1为原型创建obj
console.log(obj.__proto__);obj的原型
Object.setPrototypeOf(obj,obj2);将obj的原型改为obj2
console.log(obj.__proto__);obj的原型

const obj1={a:1obj的原型
console.log(Object.getPrototypeOf(obj));obj的原型
console.log(obj.__proto__===Object.getPrototypeOf(obj));true

const obj1={myname:"cyy"};
const obj={
    say(){
        console.log(.myname);
    }
}
Object.setPrototypeOf(obj,obj1);修改obj的原型为obj1
obj.say();


const cobj1={name:"cyy"};
const cobj={
    say(){
        console.log(`${ super.name }`);通过super访问原型对象
    }
}
Object.setPrototypeOf(cobj,cobj1);修改obj的原型为obj1
cobj.say();

对象简写，可以用super
const cobj1={name:"cyy"{
    say(){
        console.log(`${ super.name }`);
    }
}
Object.setPrototypeOf(cobj,cobj1);
cobj.say();cyy

ES5，不能用super
const nobj1={name:"cyy"};
const nobj={
    say:(){
        console.log(`${ super.name }`);
    }
}
Object.setPrototypeOf(nobj,nobj1);
nobj.say();报错


箭头函数，不能用super
const vobj1={name:"cyy"};
const vobj={
    say:()=>{
        console.log(`${ super.name }`);
    }
}
Object.setPrototypeOf(vobj,vobj1);
vobj.say();报错