Gsap Timeline

1---2name: gsap-timeline3description: Official GSAP skill for timelines — gsap.timeline(), position parameter, nesting, playback. Use when sequencing animations, choreographing keyframes, or when the user asks about animation sequencing, timelines, or animation order (in GSAP or when recommending a library that supports timelines).4license: MIT5---6 7# GSAP Timeline8 9## When to Use This Skill10 11Apply when building multi-step animations, coordinating several tweens in sequence or parallel, or when the user asks about timelines, sequencing, or keyframe-style animation in GSAP.12 13**Related skills:** For single tweens and eases use **gsap-core**; for scroll-driven timelines use **gsap-scrolltrigger**; for React use **gsap-react**.14 15## Creating a Timeline16 17```javascript18const tl = gsap.timeline();19tl.to(".a", { x: 100, duration: 1 })20  .to(".b", { y: 50, duration: 0.5 })21  .to(".c", { opacity: 0, duration: 0.3 });22```23 24By default, tweens are **appended** one after another. Use the **position parameter** to place tweens at specific times or relative to other tweens.25 26## Position Parameter27 28Third argument (or position property in vars) controls placement:29 30- **Absolute**: `1` — start at 1 second.31- **Relative (default)**: `"+=0.5"` — 0.5s after end; `"-=0.2"` — 0.2s before end.32- **Label**: `"labelName"` — at that label; `"labelName+=0.3"` — 0.3s after label.33- **Placement**: `"<"` — start when recently-added animation starts; `">"` — start when recently-added animation ends (default); `"<0.2"` — 0.2s after recently-added animation start.34 35Examples:36 37```javascript38tl.to(".a", { x: 100 }, 0);           // at 039tl.to(".b", { y: 50 }, "+=0.5");      // 0.5s after last end40tl.to(".c", { opacity: 0 }, "<");     // same start as previous41tl.to(".d", { scale: 2 }, "<0.2");    // 0.2s after previous start42```43 44## Timeline Defaults45 46Pass defaults into the timeline so all child tweens inherit:47 48```javascript49const tl = gsap.timeline({ defaults: { duration: 0.5, ease: "power2.out" } });50tl.to(".a", { x: 100 }).to(".b", { y: 50 }); // both use 0.5s and power2.out51```52 53## Timeline Options (constructor)54 55- **paused: true** — create paused; call `.play()` to start.56- **repeat**, **yoyo** — same as tweens; apply to whole timeline.57- **onComplete**, **onStart**, **onUpdate** — timeline-level callbacks.58- **defaults** — vars merged into every child tween.59 60## Labels61 62Add and use labels for readable, maintainable sequencing:63 64```javascript65tl.addLabel("intro", 0);66tl.to(".a", { x: 100 }, "intro");67tl.addLabel("outro", "+=0.5");68tl.to(".b", { opacity: 0 }, "outro");69tl.play("outro");  // start from "outro"70tl.tweenFromTo("intro", "outro"); // pauses the timeline and returns a new Tween that animates the timeline's playhead from intro to outro with no ease.71```72 73## Nesting Timelines74 75Timelines can contain other timelines.76 77```javascript78const master = gsap.timeline();79const child = gsap.timeline();80child.to(".a", { x: 100 }).to(".b", { y: 50 });81master.add(child, 0);82master.to(".c", { opacity: 0 }, "+=0.2");83```84 85## Controlling Playback86 87- **tl.play()** / **tl.pause()**88- **tl.reverse()** / **tl.progress(1)** then **tl.reverse()**89- **tl.restart()** — from start.90- **tl.time(2)** — seek to 2 seconds.91- **tl.progress(0.5)** — seek to 50%.92- **tl.kill()** — kill timeline and (by default) its children.93 94## Official GSAP Best practices95 96- ✅ Prefer timelines for sequencing97- ✅ Use the **position parameter** (third argument) to place tweens at specific times or relative to labels.98- ✅ Add **labels** with `addLabel()` for readable, maintainable sequencing.99- ✅ Pass **defaults** into the timeline constructor so child tweens inherit duration, ease, etc.100- ✅ Put ScrollTrigger on the timeline (or top-level tween), not on tweens inside a timeline.101 102## Do Not103 104- ❌ Chain animations with **delay** when a **timeline** can sequence them; prefer `gsap.timeline()` and the position parameter for multi-step animation.105- ❌ Forget to pass **defaults** (e.g. `defaults: { duration: 0.5, ease: "power2.out" }`) when many child tweens share the same duration or ease.106- ❌ Forget that **duration** on the timeline constructor is not the same as tween duration; timeline “duration” is determined by its children.107- ❌ Nest animations that contain a ScrollTrigger; ScrollTriggers should only be on top-level Tweens/Timelines.