AgentSkillsCN

gsap-sequencing

复杂的 GSAP 时间轴,包括标签、回调函数、嵌套时间轴,以及位置参数。适用于在统筹多步骤动画、构建动画序列,或创造协调一致的运动效果时使用。对于电影级动画与复杂的 UI 编排而言,这一技能至关重要。

SKILL.md
--- frontmatter
name: gsap-sequencing
description: Complex GSAP timelines including labels, callbacks, nested timelines, and position parameters. Use when orchestrating multi-step animations, building animation sequences, or creating coordinated motion. Essential for cinematic animations and complex UI choreography.

GSAP Sequencing

Complex timelines and animation orchestration.

Quick Start

javascript
import gsap from 'gsap';

const tl = gsap.timeline();

tl.to('.box1', { x: 100, duration: 0.5 })
  .to('.box2', { y: 50, duration: 0.5 })
  .to('.box3', { rotation: 360, duration: 0.5 });

Timeline Basics

Creating Timelines

javascript
// Basic timeline
const tl = gsap.timeline();

// Timeline with defaults
const tl = gsap.timeline({
  defaults: {
    duration: 0.5,
    ease: 'power2.out'
  }
});

// Paused timeline (manual control)
const tl = gsap.timeline({ paused: true });

Sequential Animations

javascript
const tl = gsap.timeline();

// Each animation starts after the previous one ends
tl.to('.header', { y: 0, opacity: 1, duration: 0.5 })
  .to('.content', { y: 0, opacity: 1, duration: 0.5 })
  .to('.footer', { y: 0, opacity: 1, duration: 0.5 });

Position Parameters

Absolute Positioning

javascript
const tl = gsap.timeline();

tl.to('.a', { x: 100 })
  .to('.b', { x: 100 }, 0)      // Start at 0 seconds (absolute)
  .to('.c', { x: 100 }, 0.5)    // Start at 0.5 seconds
  .to('.d', { x: 100 }, 2);     // Start at 2 seconds

Relative Positioning

javascript
const tl = gsap.timeline();

tl.to('.a', { x: 100, duration: 1 })
  .to('.b', { x: 100 }, '-=0.5')   // Start 0.5s before previous ends
  .to('.c', { x: 100 }, '+=0.5')   // Start 0.5s after previous ends
  .to('.d', { x: 100 }, '<')       // Start when previous starts
  .to('.e', { x: 100 }, '>')       // Start when previous ends (default)
  .to('.f', { x: 100 }, '<0.2')    // Start 0.2s after previous starts
  .to('.g', { x: 100 }, '>-0.2');  // Start 0.2s before previous ends

Position Parameter Cheat Sheet

ParameterMeaning
0At 0 seconds (absolute)
2At 2 seconds (absolute)
'+=0.5'0.5s after previous end
'-=0.5'0.5s before previous end
'<'When previous starts
'>'When previous ends
'<0.3'0.3s after previous starts
'>-0.3'0.3s before previous ends
'myLabel'At label position
'myLabel+=0.5'0.5s after label

Labels

Adding Labels

javascript
const tl = gsap.timeline();

tl.add('intro')
  .to('.title', { opacity: 1 })
  .to('.subtitle', { opacity: 1 })
  .add('content')
  .to('.paragraph', { opacity: 1 })
  .to('.image', { scale: 1 })
  .add('outro')
  .to('.cta', { y: 0 });

// Jump to label
tl.seek('content');
tl.play('outro');

Using Labels for Position

javascript
const tl = gsap.timeline();

tl.addLabel('start')
  .to('.a', { x: 100 }, 'start')
  .to('.b', { x: 100 }, 'start')      // Same time as 'a'
  .to('.c', { x: 100 }, 'start+=0.2') // 0.2s after start label
  .addLabel('middle')
  .to('.d', { x: 100 }, 'middle')
  .to('.e', { x: 100 }, 'middle-=0.1');

Nested Timelines

Basic Nesting

javascript
// Child timeline
function createIntro() {
  const tl = gsap.timeline();
  tl.from('.logo', { scale: 0, duration: 0.5 })
    .from('.tagline', { opacity: 0, y: 20 });
  return tl;
}

// Parent timeline
const master = gsap.timeline();
master.add(createIntro())
      .add(createContent())
      .add(createOutro());

Nested Timeline Positioning

javascript
const intro = gsap.timeline();
intro.to('.a', { x: 100 })
     .to('.b', { y: 100 });

const main = gsap.timeline();
main.to('.header', { opacity: 1 })
    .add(intro, '-=0.3')  // Overlap intro with header
    .to('.footer', { opacity: 1 });

Modular Animation Functions

javascript
// Reusable animation modules
const animations = {
  fadeIn: (target, duration = 0.5) => {
    return gsap.timeline()
      .from(target, { opacity: 0, y: 20, duration });
  },

  staggerIn: (targets, stagger = 0.1) => {
    return gsap.timeline()
      .from(targets, { opacity: 0, y: 30, stagger });
  },

  scaleIn: (target) => {
    return gsap.timeline()
      .from(target, { scale: 0, ease: 'back.out(1.7)' });
  }
};

// Compose master timeline
const master = gsap.timeline()
  .add(animations.fadeIn('.hero'))
  .add(animations.staggerIn('.card'), '-=0.2')
  .add(animations.scaleIn('.cta'));

Timeline Callbacks

Lifecycle Callbacks

javascript
const tl = gsap.timeline({
  onStart: () => console.log('Timeline started'),
  onUpdate: () => console.log('Frame'),
  onComplete: () => console.log('Timeline complete'),
  onRepeat: () => console.log('Timeline repeated'),
  onReverseComplete: () => console.log('Reverse complete')
});

Adding Callbacks Inline

javascript
const tl = gsap.timeline();

tl.to('.element', { x: 100 })
  .call(() => console.log('After first animation'))
  .to('.element', { y: 100 })
  .call(updateState, ['param1', 'param2'], 'labelName');

Callback with Parameters

javascript
function logProgress(label) {
  console.log(`Reached: ${label}`);
}

const tl = gsap.timeline();
tl.to('.a', { x: 100 })
  .call(logProgress, ['step1'])
  .to('.b', { x: 100 })
  .call(logProgress, ['step2']);

Timeline Control

Playback Methods

javascript
const tl = gsap.timeline({ paused: true });

// Build timeline...

// Control
tl.play();
tl.pause();
tl.resume();
tl.reverse();
tl.restart();

// Seeking
tl.seek(2);           // Jump to 2 seconds
tl.seek('labelName'); // Jump to label
tl.progress(0.5);     // Jump to 50%

// Speed
tl.timeScale(2);      // 2x speed
tl.timeScale(0.5);    // Half speed

// Direction
tl.reversed(true);    // Play backwards
tl.reversed(false);   // Play forwards

Repeat and Yoyo

javascript
const tl = gsap.timeline({
  repeat: 2,          // Repeat twice (3 total plays)
  repeatDelay: 0.5,   // Pause between repeats
  yoyo: true          // Reverse on alternate repeats
});

// Infinite loop
const tl = gsap.timeline({ repeat: -1 });

Advanced Patterns

Staggered Timeline Entries

javascript
const tl = gsap.timeline();

// Add multiple at once with stagger
tl.to('.card', {
  y: 0,
  opacity: 1,
  stagger: {
    each: 0.1,
    from: 'start'
  }
}, 'cards');

Timeline Scrubbing

javascript
const tl = gsap.timeline({ paused: true });
tl.to('.progress', { scaleX: 1, duration: 1 });

// Scrub based on input
slider.addEventListener('input', (e) => {
  tl.progress(e.target.value / 100);
});

Conditional Branches

javascript
function createTimeline(options) {
  const tl = gsap.timeline();

  tl.to('.intro', { opacity: 1 });

  if (options.showDetails) {
    tl.to('.details', { height: 'auto', opacity: 1 });
  }

  if (options.animate3D) {
    tl.to('.model', { rotationY: 360 });
  }

  tl.to('.outro', { opacity: 1 });

  return tl;
}

Complex Sequence Example

Page Transition

javascript
function pageTransition(currentPage, nextPage) {
  const tl = gsap.timeline();

  // Exit current page
  tl.to(currentPage, {
    opacity: 0,
    x: -50,
    duration: 0.3,
    ease: 'power2.in'
  })

  // Transition overlay
  .to('.overlay', {
    scaleY: 1,
    transformOrigin: 'bottom',
    duration: 0.4,
    ease: 'power2.inOut'
  }, '-=0.1')

  // Swap content (instant)
  .set(currentPage, { display: 'none' })
  .set(nextPage, { display: 'block', opacity: 0, x: 50 })

  // Hide overlay
  .to('.overlay', {
    scaleY: 0,
    transformOrigin: 'top',
    duration: 0.4,
    ease: 'power2.inOut'
  })

  // Enter next page
  .to(nextPage, {
    opacity: 1,
    x: 0,
    duration: 0.3,
    ease: 'power2.out'
  }, '-=0.2');

  return tl;
}

Orchestrated UI Reveal

javascript
function revealDashboard() {
  const tl = gsap.timeline({ defaults: { ease: 'power3.out' } });

  tl.addLabel('start')

    // Header slides down
    .from('.header', { y: -100, opacity: 0, duration: 0.6 }, 'start')

    // Sidebar slides in
    .from('.sidebar', { x: -100, opacity: 0, duration: 0.6 }, 'start+=0.1')

    // Cards stagger in
    .from('.card', {
      y: 50,
      opacity: 0,
      duration: 0.5,
      stagger: 0.1
    }, 'start+=0.2')

    // Charts animate
    .from('.chart-bar', {
      scaleY: 0,
      transformOrigin: 'bottom',
      duration: 0.4,
      stagger: 0.05
    }, 'start+=0.4')

    // Final CTA pops
    .from('.cta-button', {
      scale: 0,
      ease: 'back.out(1.7)',
      duration: 0.4
    }, '-=0.2');

  return tl;
}

Temporal Collapse Sequences

Countdown Digit Change

javascript
function digitChangeSequence(digitElement, oldValue, newValue) {
  const tl = gsap.timeline();

  tl.to(digitElement, {
    rotationX: -90,
    opacity: 0,
    textShadow: '0 0 0px #00F5FF',
    duration: 0.25,
    ease: 'power2.in'
  })
  .call(() => { digitElement.textContent = newValue; })
  .fromTo(digitElement,
    { rotationX: 90, opacity: 0 },
    {
      rotationX: 0,
      opacity: 1,
      textShadow: '0 0 30px #00F5FF',
      duration: 0.25,
      ease: 'power2.out'
    }
  )
  .to(digitElement, {
    textShadow: '0 0 10px #00F5FF',
    duration: 0.3
  });

  return tl;
}

Final Countdown Sequence

javascript
function createFinalCountdown() {
  const master = gsap.timeline({ paused: true });

  // Build intensity over last 10 seconds
  for (let i = 10; i >= 0; i--) {
    const intensity = (10 - i) / 10;

    master.addLabel(`second-${i}`)
      .to('.countdown', {
        scale: 1 + intensity * 0.2,
        textShadow: `0 0 ${20 + intensity * 40}px #00F5FF`,
        duration: 0.5
      }, `second-${i}`)
      .to('.background', {
        filter: `brightness(${1 + intensity * 0.5})`,
        duration: 0.5
      }, `second-${i}`);
  }

  // Zero moment explosion
  master.addLabel('zero')
    .to('.countdown', {
      scale: 3,
      opacity: 0,
      duration: 0.5,
      ease: 'power4.out'
    }, 'zero')
    .to('.celebration', {
      opacity: 1,
      scale: 1,
      duration: 0.8,
      ease: 'back.out(1.7)'
    }, 'zero+=0.3');

  return master;
}

Debugging Timelines

javascript
// Slow down for inspection
tl.timeScale(0.25);

// Log timeline duration
console.log('Duration:', tl.duration());

// Log all tweens
tl.getChildren().forEach((child, i) => {
  console.log(i, child.startTime(), child.duration());
});

// GSDevTools (premium plugin)
GSDevTools.create({ animation: tl });

Reference

  • See gsap-fundamentals for tween basics and easing
  • See gsap-react for React integration
  • See gsap-scrolltrigger for scroll-driven timelines