SKILL.md

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The registry key must match the composition root's data-composition-id.

Do not call tl.play() for render-critical motion.

Do not build timelines inside async code, timers, or event handlers.

Keep loops finite. HyperFrames renders finite video durations.

Core Tween Methods

gsap.to(targets, vars) — animate from current state to vars. Most common.

gsap.from(targets, vars) — animate from vars to current state (entrances).

gsap.fromTo(targets, fromVars, toVars) — explicit start and end.

gsap.set(targets, vars) — apply immediately (duration 0).

Always use camelCase property names (e.g. backgroundColor, rotationX).

Common vars

duration — seconds (default 0.5).

delay — seconds before start.

ease — "power1.out" (default), "power3.inOut", "back.out(1.7)", "elastic.out(1, 0.3)", "none".

stagger — number 0.1 or object: { amount: 0.3, from: "center" }, { each: 0.1, from: "random" }.

overwrite — false (default), true, or "auto".

repeat — finite number; never -1 in HyperFrames. Compute repeats from the visible duration. yoyo — alternates direction with repeat.

onComplete, onStart, onUpdate — callbacks.

immediateRender — default true for from()/fromTo(). Set false on later tweens targeting the same property+element to avoid overwrite.

Transforms and CSS

Prefer GSAP's transform aliases over raw transform string:

GSAP property

Equivalent

x, y, z

translateX/Y/Z (px)

xPercent, yPercent

translateX/Y in %

scale, scaleX, scaleY

scale

rotation

rotate (deg)

rotationX, rotationY

3D rotate

skewX, skewY

skew

transformOrigin

transform-origin

autoAlpha — prefer over opacity. At 0: also sets visibility: hidden.

CSS variables — "--hue": 180.

svgOrigin (SVG only) — global SVG coordinate space origin. Don't combine with transformOrigin.

Directional rotation — "360_cw", "-170_short", "90_ccw".

clearProps — "all" or comma-separated; removes inline styles on complete.

Relative values — "+=20", "-=10", "*=2".

Function-Based Values

gsap.to(".item", {

  x: (i, target, targets) => i * 50,

  stagger: 0.1,

});

Easing

Built-in eases: power1–power4, back, bounce, circ, elastic, expo, sine. Each has .in, .out, .inOut.

Defaults

gsap.defaults({ duration: 0.6, ease: "power2.out" });

Controlling Tweens

const tween = gsap.to(".box", { x: 100 });

tween.pause();

tween.play();

tween.reverse();

tween.kill();

tween.progress(0.5);

tween.time(0.2);

gsap.matchMedia() (Responsive + Accessibility)

Runs setup only when a media query matches; auto-reverts when it stops matching.

let mm = gsap.matchMedia();

mm.add(

  {

    isDesktop: "(min-width: 800px)",

    reduceMotion: "(prefers-reduced-motion: reduce)",

  },

  (context) => {

    const { isDesktop, reduceMotion } = context.conditions;

    gsap.to(".box", {

      rotation: isDesktop ? 360 : 180,

      duration: reduceMotion ? 0 : 2,

    });

  },

);

Timelines

Creating a Timeline

const tl = gsap.timeline({ defaults: { duration: 0.5, ease: "power2.out" } });

tl.to(".a", { x: 100 }).to(".b", { y: 50 }).to(".c", { opacity: 0 });

Position Parameter

Third argument controls placement:

Absolute: 1 — at 1s

Relative: "+=0.5" — after end; "-=0.2" — before end

Label: "intro", "intro+=0.3"

Alignment: "<" — same start as previous; ">" — after previous ends; "<0.2" — 0.2s after previous starts

tl.to(".a", { x: 100 }, 0);

tl.to(".b", { y: 50 }, "<"); // same start as .a

tl.to(".c", { opacity: 0 }, "<0.2"); // 0.2s after .b starts

Labels

tl.addLabel("intro", 0);

tl.to(".a", { x: 100 }, "intro");

tl.addLabel("outro", "+=0.5");

tl.play("outro");

tl.tweenFromTo("intro", "outro");

Timeline Options

paused: true — create paused; call .play() to start.

repeat, yoyo — apply to whole timeline.

defaults — vars merged into every child tween.

Nesting Timelines

const master = gsap.timeline();

const child = gsap.timeline();

child.to(".a", { x: 100 }).to(".b", { y: 50 });

master.add(child, 0);

Playback Control

tl.play(), tl.pause(), tl.reverse(), tl.restart(), tl.time(2), tl.progress(0.5), tl.kill().

Performance

Prefer Transform and Opacity

Animating x, y, scale, rotation, opacity stays on the compositor. Avoid width, height, top, left when transforms achieve the same effect.

will-change

will-change: transform;

Only on elements that actually animate.

gsap.quickTo() for Frequent Updates

let xTo = gsap.quickTo("#id", "x", { duration: 0.4, ease: "power3" }),

  yTo = gsap.quickTo("#id", "y", { duration: 0.4, ease: "power3" });

container.addEventListener("mousemove", (e) => {

  xTo(e.pageX);

  yTo(e.pageY);

});

Stagger > Many Tweens

Use stagger instead of separate tweens with manual delays.

Cleanup

Pause or kill off-screen animations.

References (loaded on demand)

references/effects.md — Drop-in effects: typewriter text, audio visualizer. Read when needing ready-made effect patterns for HyperFrames.

Best Practices

Use camelCase property names; prefer transform aliases and autoAlpha.

Prefer timelines over chaining with delay; use the position parameter.

Add labels with addLabel() for readable sequencing.

Pass defaults into timeline constructor.

Store tween/timeline return value when controlling playback.

Do Not

Animate layout properties (width/height/top/left) when transforms suffice.

Use both svgOrigin and transformOrigin on the same SVG element.

Chain animations with delay when a timeline can sequence them.

Create tweens before the DOM exists.

Skip cleanup — always kill tweens when no longer needed.

Use infinite repeat values in HyperFrames compositions. Use finite repeat counts computed from the visible duration.

Credits And References

HyperFrames adapter source: packages/core/src/runtime/adapters/gsap.ts.

GSAP documentation: https://gsap.com/docs/v3/

GSAP timeline pause and seek behavior: https://gsap.com/docs/v3/GSAP/Timeline/pause%28%29/

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