AOS (Animate On Scroll) is still downloaded about 174,000 times a week. Its last release, 2.3.4, came out in October 2018, and 3.0 never left beta. I wanted a maintained, typed version with the same animations and options, so I built reveal-on-scroll.

Quick start 

npm install reveal-on-scroll 
import ROS from 'reveal-on-scroll'; import 'reveal-on-scroll/style.css'; ROS.init(); 
<div data-ros="fade-up">I fade in when you scroll to me.</div>

No bundler? Use the CDN:

<link rel="stylesheet" href="https://unpkg.com/reveal-on-scroll/dist/reveal-on-scroll.css" /> <script src="https://unpkg.com/reveal-on-scroll/dist/reveal-on-scroll.js"></script> <script> ROS.init(); </script>

Switching from AOS

The animation names and options are the same, so it's a find-and-replace:

AOS reveal-on-scroll
npm install aos npm install reveal-on-scroll
import AOS from 'aos' import ROS from 'reveal-on-scroll'
data-aos, data-aos-* data-ros, data-ros-*
aos-init, aos-animate ros-init, ros-animate
aos:in, aos:out ros:in, ros:out

What's different

  • Size: 3.6 kB gzipped (JS 2.7 kB + CSS 0.9 kB). AOS 2.3.4 is 6.7 kB (JS 4.6 kB + CSS 2.1 kB).
  • Positions stay right. Triggers are recalculated while you scroll and when images, fonts or content load, so you don't need to call refresh().
  • Reduced motion. If the user asked for less motion, elements fade instead of moving.
  • No lost content. With JavaScript off, or if the script fails to load, everything stays visible.
  • Any timing. Durations and delays can be any number of milliseconds, and easing can be any CSS easing function.
  • Types included, ESM and UMD builds, zero dependencies.
  • Optional scroll-scrubbed mode (data-ros-scrub) using native scroll-driven animations.

Honest limits

  • The scrub mode needs CSS scroll-driven animations. At the time of writing that means Chrome 115+ and Safari 26+; Firefox only has them in preview builds.
  • It's version 0.1, so expect small API additions. The options and animation names follow AOS, so those will stay.
  • It's an independent project. It isn't affiliated with or endorsed by AOS or its author. Thank you to them for the original idea.

Links

If you use AOS today, I'd love to hear what's missing. Issues and stars are very welcome.