view-timeline-name

The view-timeline-name CSS property is used to define the name of a named view progress timeline, which is progressed through based on the change in visibility of an element (known as the subject) inside a scrollable element (scroller). view-timeline is set on the subject.

The visibility of the subject inside the scroller is tracked — by default, the timeline is at 0% when the subject is first visible at one edge of the scroller and 100% when it reaches the opposite edge. The name is then referenced in an animation-timeline declaration to indicate the element that will be animated as the timeline progresses. This can be the subject element, but it doesn't have to be — you can animate a different element as the subject moves through the scrolling area.

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 view-timeline-axis and view-timeline-name properties can also be set using the view-timeline shorthand property.

Syntax

view-timeline-name: none;
view-timeline-name: --custom_name_for_timeline;

Values

Allowed values for view-timeline-name are:

none: The timeline has no name.
<dashed-ident>: An arbitrary custom identifier defining a name for a view progress timeline, which can then be referenced in an animation-timeline property.

Note: <dashed-ident> values must start with --, which helps avoid name clashes with standard CSS keywords.

Formal definition

Initial value	none
Applies to	all elements
Inherited	no
Computed value	the keyword none or a list of CSS identifiers
Animation type	not animatable

Formal syntax

[ none | <dashed-ident> ]#

Examples

Creating a named view progress timeline

A view progress timeline named --subjectReveal is defined using the view-timeline-name property on a subject element with a class of animation. This is then set as the timeline for the same element using animation-timeline: --subjectReveal;. The result is that the subject element animates as it moves upwards through the document as it is scrolled.

HTML

The HTML for the example is shown below.

<div class="content">
  <h1>Content</h1>

  <p>
    Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod
    tempor incididunt ut labore et dolore magna aliqua. Risus quis varius quam
    quisque id. Et ligula ullamcorper malesuada proin libero nunc consequat
    interdum varius. Elit ullamcorper dignissim cras tincidunt lobortis feugiat
    vivamus at augue.
  </p>

  <p>
    Dolor sed viverra ipsum nunc aliquet. Sed sed risus pretium quam vulputate
    dignissim. Tortor aliquam nulla facilisi cras. A erat nam at lectus urna
    duis convallis convallis. Nibh ipsum consequat nisl vel pretium lectus.
    Sagittis aliquam malesuada bibendum arcu vitae elementum. Malesuada bibendum
    arcu vitae elementum curabitur vitae nunc sed velit.
  </p>

  <div class="subject animation"></div>

  <p>
    Adipiscing enim eu turpis egestas pretium aenean pharetra magna ac. Arcu
    cursus vitae congue mauris rhoncus aenean vel. Sit amet cursus sit amet
    dictum. Augue neque gravida in fermentum et. Gravida rutrum quisque non
    tellus orci ac auctor augue mauris. Risus quis varius quam quisque id diam
    vel quam elementum. Nibh praesent tristique magna sit amet purus gravida
    quis. Duis ultricies lacus sed turpis tincidunt id aliquet. In egestas erat
    imperdiet sed euismod nisi. Eget egestas purus viverra accumsan in nisl nisi
    scelerisque. Netus et malesuada fames ac.
  </p>
</div>

CSS

The subject element and its containing content element are styled minimally, and the text content is given some basic font settings:

.subject {
  width: 300px;
  height: 200px;
  margin: 0 auto;
  background-color: deeppink;
}

.content {
  width: 75%;
  max-width: 800px;
  margin: 0 auto;
}

p,
h1 {
  font-family: Arial, Helvetica, sans-serif;
}

h1 {
  font-size: 3rem;
}

p {
  font-size: 1.5rem;
  line-height: 1.5;
}

The <div> with the class of subject is also given a class of animation — this is where view-timeline-name is set to define a named view progress timeline. It is also given an animation-timeline name with the same value to declare that this will be the element animated as the view progress timeline is progressed.

Last, an animation is specified on the element that animates its opacity and scale, causing it to fade in and size up as it moves up the scroller.

.animation {
  view-timeline-name: --subjectReveal;
  animation-timeline: --subjectReveal;

  animation-name: appear;
  animation-fill-mode: both;
  animation-duration: 1ms; /* Firefox requires this to apply the animation */
}

@keyframes appear {
  from {
    opacity: 0;
    transform: scaleX(0);
  }

  to {
    opacity: 1,
    transform: scaleX(1);
  }
}

Result

Scroll to see the subject element being animated.

css properties view-timeline-name