Reflect的玩法(用来操作一个对象)

Reflect.get(target, propertyKey, receiver)

var myObj = {
    foo: 1,
    bar: 2,
    get baz(){
        return this.foo + this.bar
    }
}
let a = Reflect.get(myObj,'foo');
let b = Reflect.get(myObj,'bar');
let c = Reflect.get(myObj,'baz');
let d = Reflect.get(myObj,'name')

console.log(a,b,c,d) //1,2,3,undefined

Reflect.get中的第三个参数:

var person={
    name:"Alice",
    age: 18,
    get say(){
        console.log(this.name + "今年" + this.age)
    },
    see(){
        console.log(this.name + " 没看见该方法声明的'get' !")
    }
}

let receiverObj = {
    name: "Tom",
    age: "27"
}

Reflect.get(person, 'say', receiverObj) //会直接执行了这个方法并输出的内容：Tom今年27
Reflect.get(person, 'see', receiverObj)  // 返回定义的方法 ƒ see(){  console.log(this.name) }

Reflect.set(target, propertyKey, value, receiver)
⚠️注意:可以通过目标对象的方法去改变另一个对象的值, 功能联想下apply, call, bind

var myObj = {
    foo: 1,
    set bar(value){
        return this.foo = value;
    }
}

let receiverObj = {
    foo: 4
}

Reflect.set(myObj, 'foo', 2, receiverObj);
console.log(myObj.foo) //1
console.log(receiverObj.foo) //2

Reflect.has
⚠️：判断目标对象是否存在某个属性

let person = {
    name: 'Alice',
    age: 18
}

let property = 'name'
console.log(Reflect.has(person,property))//true
console.log(Reflect.has(person,'hobby')) //false

Reflect.ownKeys
⚠️：用来返回所有的对象里的所有属性名称

let person = {
    name: 'Alice',
    age: 18
}

console.log(Reflect.ownKeys(person)) //Array(2) ["name", "age"]