1.监听对象属性的操作（Es5）
const obj = {
name: "why",
age: 18,
height: 1.88
}
// 需求: 监听对象属性的所有操作
// 监听属性的操作
// 1.针对一个属性
// let _name = obj.name
// Object.defineProperty(obj, "name", {
// set: function(newValue) {
// console.log("监听: 给name设置了新的值:", newValue)
// _name = newValue
// },
// get: function() {
// console.log("监听: 获取name的值")
// return _name
// }
// })
// 2.监听所有的属性: 遍历所有的属性, 对每一个属性使用defineProperty
const keys = Object.keys(obj)
for (const key of keys) {
let value = obj[key]
Object.defineProperty(obj, key, {
set: function(newValue) {
console.log(`监听: 给${key}设置了新的值:`, newValue)
value = newValue
},
get: function() {
console.log(`监听: 获取${key}的值`)
return value
}
})
}
// console.log(obj.name)
// obj.name = "kobe"
console.log(obj.age)
obj.age = 17
console.log(obj.age)
// 什么是响应式?
// const nameEl = document.querySelector(".name")
// nameEl.textContent = obj.name
// obj.name = "kobe"
// obj.name = "james"
2.监听对象属性的操作（Es6）
const obj = {
name: "why",
age: 18,
height: 1.88
}
// 1.创建一个Proxy对象
const objProxy = new Proxy(obj, {
set: function(target, key, newValue) {
console.log(`监听: 监听${key}的设置值: `, newValue)
target[key] = newValue
},
get: function(target, key) {
console.log(`监听: 监听${key}的获取`)
return target[key]
}
})
// 2.对obj的所有操作, 应该去操作objProxy
// console.log(objProxy.name)
// objProxy.name = "kobe"
// console.log(objProxy.name)
// objProxy.name = "james"
objProxy.address = "广州市"
console.log(objProxy.address)
3.Proxy-其他捕获器的监听方法
const obj = {
name: "why",
age: 18,
height: 1.88
}
// 1.创建一个Proxy对象
const objProxy = new Proxy(obj, {
set: function(target, key, newValue) {
console.log(`监听: 监听${key}的设置值: `, newValue)
target[key] = newValue
},
get: function(target, key) {
console.log(`监听: 监听${key}的获取`)
return target[key]
},
deleteProperty: function(target, key) {
console.log(`监听: 监听删除${key}属性`)
delete obj.name
},
has: function(target, key) {
console.log(`监听: 监听in判断 ${key}属性`)
return key in target
}
})
delete objProxy.name
console.log("age" in objProxy)
4.Proxy-监听函数对象的操作
function foo(num1, num2) {
console.log(this, num1, num2)
}
const fooProxy = new Proxy(foo, {
apply: function(target, thisArg, otherArgs) {
console.log("监听执行了apply操作")
target.apply(thisArg, otherArgs)
},
construct: function(target, otherArray) {
console.log("监听执行了new操作")
console.log(target, otherArray)
return new target(...otherArray)
}
})
// fooProxy.apply("abc", [111, 222])
new fooProxy("aaa", "bbb")
5.Reflect-和Object的区别之一
"use strict"
const obj = {
name: "why",
age: 18
}
Object.defineProperty(obj, "name", {
configurable: false
})
// Reflect.defineProperty()
// 1.用以前的方式进行操作
// delete obj.name
// if (obj.name) {
// console.log("name没有删除成功")
// } else {
// console.log("name删除成功")
// }
// 2.Reflect
if (Reflect.deleteProperty(obj, "name")) {
console.log("name删除成功")
} else {
console.log("name没有删除成功")
}
6.Reflect-和Proxy共同完成代理
const obj = {
name: "why",
age: 18
}
const objProxy = new Proxy(obj, {
set: function(target, key, newValue, receiver) {
// target[key] = newValue
// 1.好处一: 代理对象的目的: 不再直接操作原对象
// 2.好处二: Reflect.set方法有返回Boolean值, 可以判断本次操作是否成功
const isSuccess = Reflect.set(target, key, newValue)
if (!isSuccess) {
throw new Error(`set ${key} failure`)
}
},
get: function(target, key, receiver) {
}
})
// 操作代理对象
objProxy.name = "kobe"
console.log(obj)
7.Reflect-Reflect设置receiver
const obj = {
_name: "why",
set name(newValue) {
console.log("this:", this) // 默认是obj
this._name = newValue
},
get name() {
return this._name
}
}
// obj.name = "aaaa"
// console.log(obj.name)
// obj.name = "kobe"
const objProxy = new Proxy(obj, {
set: function(target, key, newValue, receiver) {
// target[key] = newValue
// 1.好处一: 代理对象的目的: 不再直接操作原对象
// 2.好处二: Reflect.set方法有返回Boolean值, 可以判断本次操作是否成功
/*
3.好处三:
> receiver就是外层Proxy对象
> Reflect.set/get最后一个参数, 可以决定对象访问器setter/getter的this指向
*/
console.log("proxy中设置方法被调用")
const isSuccess = Reflect.set(target, key, newValue, receiver)
if (!isSuccess) {
throw new Error(`set ${key} failure`)
}
},
get: function(target, key, receiver) {
console.log("proxy中获取方法被调用")
return Reflect.get(target, key, receiver)
}
})
// 操作代理对象
objProxy.name = "kobe"
console.log(objProxy.name)
8.Reflect-和construct结合的反射
function Person(name, age) {
this.name = name
this.age = age
}
function Student(name, age) {
// Person.call(this, name, age)
const _this = Reflect.construct(Person, [name, age], Student)
return _this
}
// const stu = new Student("why", 18)
const stu = new Student("why", 18)
console.log(stu)
console.log(stu.__proto__ === Student.prototype)
