lazyload VS lazysizes

I made a 826 byte library a while back that supports , , and css background images: https://github.com/fromtheoutfit/lazyload

Use a JavaScript library to implement lazy loading. There are a number of JavaScript libraries available that can help you implement lazy loading, such as Lazysizes and Lozad.

Normally I would write some client-side JS to do this but as this project is solely server-rendered I opted to use a simple tried-and-true library for this: lazysizes.

I recently did some optimizations on my personal website to make the images load “lazily.” In other words it only loads stuff once it hits the viewport. I think that’s what you’re looking for. I tried two techniques:

1. There is an HTML attribute to do just this and it seems to work for iframes too: https://developer.mozilla.org/en-US/docs/Web/Performance/Laz...

2. There is a simple library called “lazy sizes” (https://github.com/aFarkas/lazysizes)

I tried to avoid the lib and use the native HTML… but for whatever reason the lib worked more reliably/effectively in manual tests as well as in my benchmarking via PageSpeed / Lighthouse. YMMV!

lazysizes is better than loading="lazy"

Since browsers support native lazy-loading, do we need libraries like this https://github.com/aFarkas/lazysizes?

Use Lazy loading for below-the-fold images. (You can use different 3rd party libraries like Unveil, lazysizes, etc.)

⚡️ Lazy load images with lazysizes

You can also use this really great library for handling the loading of images in a holistic and well-supported way or you can look at manually implementing the LQIP technique.

And, lazyloading is only for images. If you use e.g. lazysizes you can do anything with it. I'm a digital publisher so I use it for ads and embedded tweets/IGs and so on.