ScrollTimeline

The ScrollTimeline interface of the {{domxref("Web Animations API", "Web Animations API", "", "nocode")}} represents a scroll progress timeline (see CSS scroll-driven animations for more details).

Pass a ScrollTimeline instance to the {{domxref("Animation.Animation", "Animation()")}} constructor or the {{domxref("Element.animate()", "animate()")}} method to specify it as the timeline that will control the progress of the animation.

Constructor

{{domxref("ScrollTimeline.ScrollTimeline", "ScrollTimeline()")}}
- : Creates a new ScrollTimeline object instance.

Instance properties

This interface also inherits the properties of its parent, {{domxref("AnimationTimeline")}}.

{{domxref("ScrollTimeline.source", "source")}} {{ReadOnlyInline}}
- : Returns a reference to the scrollable element (scroller) whose scroll position is driving the progress of the timeline and therefore the animation.
{{domxref("ScrollTimeline.axis", "axis")}} {{ReadOnlyInline}}
- : Returns an enumerated value representing the scroll axis that is driving the progress of the timeline.

Instance methods

This interface inherits the methods of its parent, {{domxref("AnimationTimeline")}}.

Examples

Displaying the source and axis of a scroll progress timeline

In this example, we animate an element with a class of box along a view progress timeline — it animates across the screen as the document scrolls. We output the source element and scroll axis to an output element in the top-right corner.

HTML

The HTML for the example is shown below.

html

<div class="content"></div>
<div class="box"></div>
<div class="output"></div>

CSS

The CSS for the example looks like this:

css

.content {
  height: 2000px;
}

.box {
  width: 100px;
  height: 100px;
  border-radius: 10px;
  background-color: rebeccapurple;
  position: fixed;
  top: 20px;
  left: 0%;
}

.output {
  font-family: "Helvetica", "Arial", sans-serif;
  position: fixed;
  top: 5px;
  right: 5px;
}

JavaScript

In the JavaScript, we grab references to the box and output <div>s, then create a new ScrollTimeline, specifying that the element that will drive the scroll timeline progress is the document ({{htmlelement("html")}}) element, and the scroll axis is the block axis. We then animate the box element with the Web Animations API. Last of all, we display the source element and axis in the output element.

const box = document.querySelector(".box");
const output = document.querySelector(".output");

const timeline = new ScrollTimeline({
  source: document.documentElement,
  axis: "block",
});

box.animate(
  {
    rotate: ["0deg", "720deg"],
    left: ["0%", "100%"],
  },
  {
    timeline,
  },
);

output.textContent = `Timeline source element: ${timeline.source.nodeName}. Timeline scroll axis: ${timeline.axis}`;

Result

Scroll to see the box being animated.

{{EmbedLiveSample("Displaying the source and axis of a scroll progress timeline", "100%", "320px")}}