前端面试题（二十七）js怎么控制加载一张图片，加载完后再加载下一张

<script type="text/javascript">
    let img = new Image();
    img.src="https://ss3.baidu.com/-rVXeDTa2gU2pMbgoY3K/it/u=2338809465,934935445&fm=202&src=608&mola=new&crop=v1";
    img.onload = function () {
        alert('图片的宽为：'+img.width+'；图片的高度为：'+img.height);
        document.getElementById("mypic").innerHTML="<img src='"+this.src+"'/>";
    }
</script>
<div id="mypic">onloading....</div>