Tip: Lazy load images in HTML

Images are nowadays a crucial part of any webpage, but, as with most things, they come at a cost. Images are usually a major percentage of a page's load, which is why they make for a great candidate for optimization. The most common technique is that of lazy loading, usually in the form of delaying loading images outside the initial viewport until they are close to being scrolled into view.

This exact behavior is already part of the HTML standard in the form of the loading attribute. All you have to do to reap its benefits is add loading="lazy" to any images you want to add lazy loading to:

<img src="/img/duck.png" alt="A rubber duck" loading="lazy" />

Caveat: At the time of writing, the loading attribute is supported in most modern browsers, except for Safari, but not in legacy browsers, such as IE. On that note, lazy loading can be seen as a progressive enhancement for browsers that support it, so it's still worth adding for any users that can benefit from it.