js不需要知道图片宽高的懒加载方法
懒加载是如何实现的？ - 简书
https://www.jianshu.com/p/e86c61468285
找到一个不需要知道图片宽高的懒加载方法了（经过实际测试，不加宽高仍然是无法正常加载的，设置height:auto,height:100%，仍然显示高度为0）
dinbror/blazy: Hey, be lazy! bLazy.JS is a lightweight pure JavaScript script for lazy loading and multi-serving images. It's working in all modern browsers including IE7+.
https://github.com/dinbror/blazy#demo
这个兼容性比较好
<script type="text/javascript" src="https://cdn.jsdelivr.net/blazy/latest/blazy.min.js"></script>
How to lazyload
Add blazy.js to your website
Add the 'b-lazy' class to the elements that should be lazy loaded
Initialize blazy whenever you're ready
var bLazy = new Blazy({
// Options
});
<img class="b-lazy" data-src="data:image.jpg" />
http://dinbror.dk/blazy/examples/?ref=github#image
注：vuejs，react有对应的懒加载插件
twobin/react-lazyload: Lazy load your component, image or anything matters the performance.
https://github.com/twobin/react-lazyload