/* 代理模式* 由于对象不能直接引用另一个对象，所以需要通过代理对象在这两个对象之间起到中介作用* 可以在使用者和目标对象之间加一个代理对象，通过代理可以实现控制*/class Google {    get(url) {        return 'google';    }}class Proxy {    constructor() {        this.google = new Google();    }    get(url) {        return this.google.get(url)    }}let proxy = new Proxy()let result = proxy.get('http://www.google.com');console.log(result);复制代码

代理缓存

/* 反向代理* 负载均衡* 保护内部信息*/let sum = (function (n) {    let cache = {};    function multi(n) {        if (n <= 1) return 1;        return n * cache[n - 1] || multi(n - 1);    }    return function () {        let result = 0;        for (let i = 1; i <= n; i++) {            let res = multi(i);            cache[i] = res;            result += res;        }        return result;    }})()console.time('cost')console.log(sum(10000))console.timeEnd('cost')复制代码

es6 Proxy

let wangyan = {    name: 'wangyan',    age: 30,    height: 165,};let wangmama = new Proxy(wangyan, {    get(target, key) {        if (key === 'age') {            return target.age - 2;        } else if (key === 'height') {            return target.height + 3;        } else {            return target[key];        }    },    set(target, key, value) {        if (key === 'bf') {            let bf = value;            if (bf.age > 40) {                throw new Error('too old')            } else if (bf.height < 175) {                throw new Error('too low')            } else {                target.bf = bf;            }        }    }});console.log(wangmama.age)console.log(wangmama.bf = {    age: 50})复制代码