<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>