lazySizes is the ultimate and lightweight lazyLoader which lazy loads images (including responsive images (picture/srcset)), iframes and scripts. The plugin detects any visibility changes triggered through user interaction, CSS or JavaScript without configuration. Due to the fact that it can also automatically calculate the sizes attribute for your responsive images, it helps to seperate layout (CSS) from content/structure (HTML) and makes integrating responsive images into any environment simply simple.

lazysizes High Performance Responsive Lazy Loader For Images

Demo Website