class MyImage{

    constructor() {

        this.img =new Image();

        document.body.appendChild(this.img);

    }

    setSrc(src) {

        this.img.src = src;

    }

}

//代理模式实现

class ProxyImage{

    constructor() {

        this.proxyImage =new Image();

    }

    setSrc(src) {

        let myImageObj =new MyImage();

        //本地临时图片

        myImageObj.img.src ='https://n.sinaimg.cn/sinacn10116/600/w1920h1080/20190326/2c30-hutwezf6832339.jpg'

        this.proxyImage.src = src;

        this.proxyImage.onload =function () {

            myImageObj.img.src = src;

        }

    }

}

// let myImage=new MyImage();

// myImage.setSrc('https://seopic.699pic.com/photo/40250/3909.jpg_wh1200.jpg');

let proxyImage =new ProxyImage();

proxyImage.setSrc('https://seopic.699pic.com/photo/40250/3909.jpg_wh1200.jpg')