Gsap Timeline

# GSAP Timeline

## When to Use This Skill

Apply 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.

**Related skills:** For single tweens and eases use **gsap-core**; for scroll-driven timelines use **gsap-scrolltrigger**; for React use **gsap-react**.

## Creating a Timeline

```javascript const tl = gsap.timeline(); tl.to(".a", { x: 100, duration: 1 }) .to(".b", { y: 50, duration: 0.5 }) .to(".c", { opacity: 0, duration: 0.3 }); ```

By default, tweens are **appended** one after another. Use the **position parameter** to place tweens at specific times or relative to other tweens.

## Position Parameter

Third argument (or position property in vars) controls placement:

- **Absolute**: `1` — start at 1 second. - **Relative (default)**: `"+=0.5"` — 0.5s after end; `"-=0.2"` — 0.2s before end. - **Label**: `"labelName"` — at that label; `"labelName+=0.3"` — 0.3s after label. - **Placement**: `"<"` — start when recently-added animation starts; `">"` — start when recently-added animation ends (default); `"<0.2"` — 0.2s after recently-added animation start.

Examples:

```javascript tl.to(".a", { x: 100 }, 0); // at 0 tl.to(".b", { y: 50 }, "+=0.5"); // 0.5s after last end tl.to(".c", { opacity: 0 }, "<"); // same start as previous tl.to(".d", { scale: 2 }, "<0.2"); // 0.2s after previous start ```

## Timeline Defaults

Pass defaults into the timeline so all child tweens inherit:

```javascript const tl = gsap.timeline({ defaults: { duration: 0.5, ease: "power2.out" } }); tl.to(".a", { x: 100 }).to(".b", { y: 50 }); // both use 0.5s and power2.out ```

## Timeline Options (constructor)

- **paused: true** — create paused; call `.play()` to start. - **repeat**, **yoyo** — same as tweens; apply to whole timeline. - **onComplete**, **onStart**, **onUpdate** — timeline-level callbacks. - **defaults** — vars merged into every child tween.

## Labels

Add and use labels for readable, maintainable sequencing:

```javascript tl.addLabel("intro", 0); tl.to(".a", { x: 100 }, "intro"); tl.addLabel("outro", "+=0.5"); tl.to(".b", { opacity: 0 }, "outro"); tl.play("outro"); // start from "outro" tl.tweenFromTo("intro", "outro"); // pauses the timeline and returns a new Tween that animates the timeline's playhead from intro to outro with no ease. ```

## Nesting Timelines

Timelines can contain other timelines.

```javascript const master = gsap.timeline(); const child = gsap.timeline(); child.to(".a", { x: 100 }).to(".b", { y: 50 }); master.add(child, 0); master.to(".c", { opacity: 0 }, "+=0.2"); ```

## Controlling Playback

- **tl.play()** / **tl.pause()** - **tl.reverse()** / **tl.progress(1)** then **tl.reverse()** - **tl.restart()** — from start. - **tl.time(2)** — seek to 2 seconds. - **tl.progress(0.5)** — seek to 50%. - **tl.kill()** — kill timeline and (by default) its children.

## Official GSAP Best practices

- ✅ Prefer timelines for sequencing - ✅ Use the **position parameter** (third argument) to place tweens at specific times or relative to labels. - ✅ Add **labels** with `addLabel()` for readable, maintainable sequencing. - ✅ Pass **defaults** into the timeline constructor so child tweens inherit duration, ease, etc. - ✅ Put ScrollTrigger on the timeline (or top-level tween), not on tweens inside a timeline.

## Do Not

- ❌ Chain animations with **delay** when a **timeline** can sequence them; prefer `gsap.timeline()` and the position parameter for multi-step animation. - ❌ Forget to pass **defaults** (e.g. `defaults: { duration: 0.5, ease: "power2.out" }`) when many child tweens share the same duration or ease. - ❌ Forget that **duration** on the timeline constructor is not the same as tween duration; timeline “duration” is determined by its children. - ❌ Nest animations that contain a ScrollTrigger; ScrollTriggers should only be on top-level Tweens/Timelines.