Animejs

Anime.js for FrameVideo

When To Use

Use Anime.js for:

• Lightweight animations — smaller bundle size than GSAP (17KB vs 45KB)
• Simple DOM/SVG motion — element entrances, transforms, opacity
• Compact syntax — cleaner for straightforward animations
• Porting Anime.js examples — user provides Anime.js code to adapt
• File size constraints — when every KB matters

Do NOT Use

Avoid Anime.js for:

• Complex timeline sequencing — GSAP has better timeline control and labels
• Default choice — use gsap unless you have specific reason for Anime.js
• 3D or WebGL — use three
• CSS-only decoration — use css-animations
• GPU shaders — use typegpu

Quick Start

Basic Anime.js animation in FrameVideo:

<div class="clip" data-start="0" data-duration="3">
  <div class="mark">Animate me</div>
</div>

<script src="https://cdn.jsdelivr.net/npm/animejs@4.0.2/lib/anime.iife.min.js"></script>
<script>
  const anim = anime({
    targets: ".mark",
    translateX: 280,
    rotate: "1turn",
    opacity: [0, 1],
    duration: 1200,
    easing: "easeOutExpo",
    autoplay: false,  // REQUIRED for FrameVideo
  });

  window.__fvAnime = window.__fvAnime || [];
  window.__fvAnime.push(anim);  // Register for seeking
</script>

Key points:

1. Set autoplay: false
2. Register on window.__fvAnime array
3. Use finite durations

Contract

• Create animations or timelines synchronously during composition initialization.
• Set autoplay: false so Anime.js does not advance on its own clock.
• Register every returned animation or timeline on window.__fvAnime.
• Use finite durations and loop counts.
• Avoid callbacks that mutate DOM based on wall-clock time, network state, or unseeded randomness.

The adapter seeks every registered instance with instance.seek(timeMs), where timeMs is FrameVideo time in milliseconds.

Basic Pattern

<script src="https://cdn.jsdelivr.net/npm/animejs@4.0.2/lib/anime.iife.min.js"></script>
<script>
  const anim = anime({
    targets: ".mark",
    translateX: 280,
    rotate: "1turn",
    opacity: [0, 1],
    duration: 1200,
    easing: "easeOutExpo",
    autoplay: false,
  });

  window.__fvAnime = window.__fvAnime || [];
  window.__fvAnime.push(anim);
</script>

Timeline Pattern

<script>
  const tl = anime.timeline({
    autoplay: false,
    easing: "easeOutCubic",
  });

  tl.add({
    targets: ".title",
    translateY: [40, 0],
    opacity: [0, 1],
    duration: 650,
  }).add(
    {
      targets: ".accent",
      scaleX: [0, 1],
      duration: 450,
    },
    250,
  );

  window.__fvAnime = window.__fvAnime || [];
  window.__fvAnime.push(tl);
</script>

Module Builds

If you use an ES module build, the adapter does not care how the instance was created. It only needs the returned object to expose seek(), pause(), and preferably play():

<script type="module">
  import { animate } from "https://cdn.jsdelivr.net/npm/animejs/+esm";

  const anim = animate(".chip", {
    x: "18rem",
    duration: 900,
    autoplay: false,
  });

  window.__fvAnime = window.__fvAnime || [];
  window.__fvAnime.push(anim);
</script>

Good Uses

• Small SVG and DOM flourishes where Anime.js syntax is compact.
• Imported Anime.js examples that can be made seek-driven.
• Multiple independent micro-animations pushed into the same registry.

Use GSAP for complex scene sequencing unless the user specifically asks for Anime.js. GSAP is still the primary FrameVideo authoring path.

Avoid

• Leaving autoplay at the Anime.js default.
• Depending on anime.running auto-discovery instead of explicit window.__fvAnime.push(...).
• Infinite loops. Compute a finite repeat count from the composition duration.
• Building animations in timers, promises, event handlers, or after async asset loads.

Validation

After editing a composition that uses Anime.js:

npx framevideo lint
npx framevideo validate

Validation

After writing Anime.js animations:

npx framevideo lint      # Check registration
npx framevideo validate  # Check runtime errors
npx framevideo preview   # Scrub timeline to verify seekability

Manual checks:

1. Registration — verify all animations pushed to window.__fvAnime
2. Autoplay disabled — all animations have autoplay: false
3. Finite loops — no infinite loop: true, use counted loops
4. Seekability — scrub preview, animation holds at any frame

Credits And References

• FrameVideo adapter source: packages/core/src/runtime/adapters/animejs.ts.
• Anime.js documentation for autoplay, pause(), and seek(): https://animejs.com/documentation/