The Future of CSS: Scroll-Linked Animations with @scroll-timeline (Part 4)

🚨 UPDATE: The Scroll-Linked Animations Specification and its proposed syntax have undergone a major rewrite. This post details an older version of the syntax and has not been updated to reflect these changes.

Do note that the concept of a Scroll-Linked Animation still stands, it’s only the syntax that has changed since writing this. Please refer to for an article with examples that use the updated syntax.

Just before I left on holiday, the 2nd article I wrote for CSS-Tricks got published. In it, I take a look at the JavaScript side of the Scroll-Linked Animations specification.

With WAAPI + ScrollTimeline, a typical “progressbar as you scroll” can be coded like this:

const myScrollTimeline = new ScrollTimeline({
  source: document.scrollingElement,
  orientation: 'block',
  scrollOffsets: [
    new CSSUnitValue(0, 'percent'),
    new CSSUnitValue(100, 'percent'),

    transform: ["scaleX(0)", "scaleX(1)"]
    duration: 1, 
    fill: "forwards", 
    timeline: myScrollTimeline

Find the details in the article.

Scroll-Linked Animations With the Web Animations API (WAAPI) and ScrollTimeline →

Published by Bramus!

Bramus is a frontend web developer from Belgium, working as a Chrome Developer Relations Engineer at Google. From the moment he discovered view-source at the age of 14 (way back in 1997), he fell in love with the web and has been tinkering with it ever since (more …)

Unless noted otherwise, the contents of this post are licensed under the Creative Commons Attribution 4.0 License and code samples are licensed under the MIT License

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