Just include a 6KB lazysizes.js, add class ‘lazyload’ to your images tag, ‘src’ attribute for low quality image (for fast default loading time), ‘data-src’ for the actual image file, da dang that’s all!
lazySizes support responsive image also by using the ‘picture’ and ‘srcset’ data attribute, see the official documentation for detail usage.
Thanks Alexander Farkas who create this high performance lazy loader for free and open source.
lazySizes is released under MIT license.
Source: Read more about lazySizes