scroll-timeline-axis

Experimental: This is an experimental technology
Check the Browser compatibility table carefully before using this in production.

The scroll-timeline-axis CSS property is used to specify the scrollbar direction that will be used to provide the timeline for a scroll-driven animation.

In a scroll-timeline animation, the animation progress is determined by a scrollbar position rather than time or some other dimension. The scroll-timeline-name property defines a name that can be used to identify an element as the source of a scroll-timeline; the scroll-timeline-axis defines the direction of the scrollbar in the container that will provide the timeline.

Note: If the element does not overflow its container in the axis dimension or if the overflow is hidden or clipped, no timeline will be created.

The scroll-timeline-axis (and scroll-timeline-name) property can also be set using the scroll-timeline shorthand property.

Syntax

scroll-timeline-axis: block;
scroll-timeline-axis: inline;
scroll-timeline-axis: vertical;
scroll-timeline-axis: horizontal;

Values

Allowed values for the scroll-timeline-axis are:

block: Represents the scrollbar in the block axis of the scroll container. This is the default value. The block axis is the direction perpendicular to the flow of text within a line. For horizontal writing modes, such as standard English, this is the same as vertical, while for vertical writing modes, it is the same as horizontal.
inline: Represents the scrollbar in the inline axis of the scroll container. The inline axis is the direction parallel to the flow of text in a line. For horizontal writing modes, this is the same as the horizontal axis, while for vertical writing modes, this is the same as vertical.
vertical: Represents the scrollbar in the vertical axis of the scroll container.
horizontal: Represents the scrollbar in the horizontal axis of the scroll container.

Formal definition

Initial value	`block`
Applies to	scroll containers
Inherited	no
Computed value	as specified
Animation type	Not animatable

Formal syntax

scroll-timeline-axis = 
  block       |
  inline      |
  vertical    |
  horizontal

Examples

Defining the axis of the scroll timeline

In this example, a scroll timeline named squareTimeline is defined using the scroll-timeline-name property on the element with the ID container, and then this name is applied to the animation on the #square element using animation-timeline: squareTimeline.

To demonstrate the effect of scroll-timeline-axis, a horizontal (non-default) scrollbar is used in this example to drive the rotation of the square.

HTML

The HTML for the example is shown below.

<div id="container">
  <div id="square"></div>
  <div id="stretcher"></div>
</div>

CSS

The CSS for the container sets it as the source of a scroll timeline named squareTimeline using the scroll-timeline-name property. The scroll axis is set by scroll-timeline-axis: horizontal; so that the horizontal scrollbar position will determine the animation timeline.

The height and width of the container are set to 200px. The container is also set to create scrollbars if it overflows (the CSS height and width rules on the stretcher element below make the content overflow its container).

#container {
  height: 200px;
  width: 200px;
  overflow: scroll;
  scroll-timeline-name: squareTimeline;
  scroll-timeline-axis: horizontal;
}

The CSS below defines a square that rotates according to the timeline provided by the animation-timeline property, which is set to the squareTimeline timeline named above.

#square {
  background-color: deeppink;
  width: 100px;
  height: 100px;
  margin-top: 100px;
  animation-name: rotateAnimation;
  animation-duration: 1ms;
  animation-timeline: squareTimeline;
  position: absolute;
  bottom: 50px;
}

#stretcher {
  height: 200px;
  width: 200px;
  background: #dedede;
}

@keyframes rotateAnimation {
  from {
    transform: rotate(0deg);
  }

  to {
    transform: rotate(360deg);
  }
}

The stretcher CSS rule sets the block height and width to values large enough to create content that overflows the container element, thereby creating scroll bars. Without this element, the content would not overflow the container, there would be no scrollbar, and hence no scroll timeline to associate with the animation timeline.

Result

Scroll the horizontal bar at the bottom to see the square animate as you scroll.

Specifications

Specification
Scroll-linked Animations # propdef-scroll-timeline-axis

Browser compatibility

BCD tables only load in the browser