GSAP Animation Skill

File Organization: This skill uses split structure. See references/ for advanced patterns.

1. Overview

This skill provides GSAP (GreenSock Animation Platform) expertise for creating smooth, professional animations in the JARVIS AI Assistant HUD.

Risk Level: LOW - Animation library with minimal security surface

Primary Use Cases:

• HUD panel entrance/exit animations
• Status indicator transitions
• Data visualization animations
• Scroll-triggered effects
• Complex timeline sequences

2. Core Responsibilities

2.1 Fundamental Principles

1. TDD First: Write animation tests before implementation
2. Performance Aware: Use transforms/opacity for GPU acceleration, avoid layout thrashing
3. Cleanup Required: Always kill animations on component unmount
4. Timeline Organization: Use timelines for complex sequences
5. Easing Selection: Choose appropriate easing for HUD feel
6. Accessibility: Respect reduced motion preferences
7. Memory Management: Avoid memory leaks with proper cleanup

2.5 Implementation Workflow (TDD)

Step 1: Write Failing Test First

// tests/animations/panel-animation.test.ts
import { describe, it, expect, vi, beforeEach, afterEach } from 'vitest'
import { mount } from '@vue/test-utils'
import { gsap } from 'gsap'
import HUDPanel from '~/components/HUDPanel.vue'

describe('HUDPanel Animation', () => {
  beforeEach(() => {
    // Mock reduced motion
    Object.defineProperty(window, 'matchMedia', {
      writable: true,
      value: vi.fn().mockImplementation(query => ({
        matches: false,
        media: query
      }))
    })
  })

  afterEach(() => {
    // Verify cleanup
    gsap.globalTimeline.clear()
  })

  it('animates panel entrance with correct properties', async () => {
    const wrapper = mount(HUDPanel)

    // Wait for animation to complete
    await new Promise(resolve => setTimeout(resolve, 600))

    const panel = wrapper.find('.hud-panel')
    expect(panel.exists()).toBe(true)
  })

  it('cleans up animations on unmount', async () => {
    const wrapper = mount(HUDPanel)
    const childCount = gsap.globalTimeline.getChildren().length

    await wrapper.unmount()

    // All animations should be killed
    expect(gsap.globalTimeline.getChildren().length).toBeLessThan(childCount)
  })

  it('respects reduced motion preference', async () => {
    // Mock reduced motion enabled
    window.matchMedia = vi.fn().mockImplementation(() => ({
      matches: true
    }))

    const wrapper = mount(HUDPanel)
    const panel = wrapper.find('.hud-panel').element

    // Should set final state immediately without animation
    expect(gsap.getProperty(panel, 'opacity')).toBe(1)
  })
})

Step 2: Implement Minimum to Pass

// components/HUDPanel.vue - implement animation logic
const animation = ref<gsap.core.Tween | null>(null)

onMounted(() => {
  if (!panelRef.value) return

  if (window.matchMedia('(prefers-reduced-motion: reduce)').matches) {
    gsap.set(panelRef.value, { opacity: 1 })
    return
  }

  animation.value = gsap.from(panelRef.value, {
    opacity: 0,
    y: 20,
    duration: 0.5
  })
})

onUnmounted(() => {
  animation.value?.kill()
})

Step 3: Refactor Following Patterns

// Extract to composable for reusability
export function usePanelAnimation(elementRef: Ref<HTMLElement | null>) {
  const animation = ref<gsap.core.Tween | null>(null)

  const animate = () => {
    if (!elementRef.value) return

    if (window.matchMedia('(prefers-reduced-motion: reduce)').matches) {
      gsap.set(elementRef.value, { opacity: 1 })
      return
    }

    animation.value = gsap.from(elementRef.value, {
      opacity: 0,
      y: 20,
      duration: 0.5,
      ease: 'power2.out'
    })
  }

  onMounted(animate)
  onUnmounted(() => animation.value?.kill())

  return { animation }
}

Step 4: Run Full Verification

# Run animation tests
npm test -- --grep "Animation"

# Check for memory leaks
npm run test:memory

# Verify 60fps performance
npm run test:performance

3. Technology Stack & Versions

3.1 Recommended Versions

3.2 Vue Integration

// plugins/gsap.ts
import { gsap } from 'gsap'
import { ScrollTrigger } from 'gsap/ScrollTrigger'

export default defineNuxtPlugin(() => {
  gsap.registerPlugin(ScrollTrigger)

  return {
    provide: {
      gsap,
      ScrollTrigger
    }
  }
})

4. Implementation Patterns

4.1 Panel Entrance Animation

<script setup lang="ts">
import { gsap } from 'gsap'
import { onMounted, onUnmounted, ref } from 'vue'

const panelRef = ref<HTMLElement | null>(null)
let animation: gsap.core.Tween | null = null

onMounted(() => {
  if (!panelRef.value) return

  // ✅ Check reduced motion preference
  if (window.matchMedia('(prefers-reduced-motion: reduce)').matches) {
    gsap.set(panelRef.value, { opacity: 1 })
    return
  }

  animation = gsap.from(panelRef.value, {
    opacity: 0,
    y: 20,
    scale: 0.95,
    duration: 0.5,
    ease: 'power2.out'
  })
})

// ✅ Cleanup on unmount
onUnmounted(() => {
  animation?.kill()
})
</script>

<template>
  <div ref="panelRef" class="hud-panel">
    <slot />
  </div>
</template>

4.2 Status Indicator Animation

// composables/useStatusAnimation.ts
import { gsap } from 'gsap'

export function useStatusAnimation(element: Ref<HTMLElement | null>) {
  const timeline = ref<gsap.core.Timeline | null>(null)

  const animateStatus = (status: string) => {
    if (!element.value) return

    timeline.value?.kill()

    timeline.value = gsap.timeline()

    switch (status) {
      case 'active':
        timeline.value
          .to(element.value, {
            scale: 1.2,
            duration: 0.2,
            ease: 'power2.out'
          })
          .to(element.value, {
            scale: 1,
            duration: 0.3,
            ease: 'elastic.out(1, 0.3)'
          })
        break

      case 'warning':
        timeline.value.to(element.value, {
          backgroundColor: '#f59e0b',
          boxShadow: '0 0 10px #f59e0b',
          duration: 0.3,
          repeat: 2,
          yoyo: true
        })
        break

      case 'error':
        timeline.value.to(element.value, {
          x: -5,
          duration: 0.05,
          repeat: 5,
          yoyo: true
        })
        break
    }
  }

  onUnmounted(() => {
    timeline.value?.kill()
  })

  return { animateStatus }
}

4.3 Data Visualization Animation

<script setup lang="ts">
import { gsap } from 'gsap'

const props = defineProps<{
  data: number[]
}>()

const barsRef = ref<HTMLElement[]>([])
let animations: gsap.core.Tween[] = []

watch(() => props.data, (newData) => {
  // Kill previous animations
  animations.forEach(a => a.kill())
  animations = []

  // Animate each bar
  newData.forEach((value, index) => {
    const bar = barsRef.value[index]
    if (!bar) return

    const tween = gsap.to(bar, {
      height: `${value}%`,
      duration: 0.5,
      delay: index * 0.05,
      ease: 'power2.out'
    })

    animations.push(tween)
  })
}, { immediate: true })

onUnmounted(() => {
  animations.forEach(a => a.kill())
})
</script>

<template>
  <div class="flex items-end h-40 gap-1">
    <div
      v-for="(_, index) in data"
      :key="index"
      ref="barsRef"
      class="w-4 bg-jarvis-primary"
    />
  </div>
</template>

4.4 Timeline Sequence

// Create complex HUD startup sequence
export function createStartupSequence(elements: {
  logo: HTMLElement
  panels: HTMLElement[]
  status: HTMLElement
}): gsap.core.Timeline {
  const tl = gsap.timeline({
    defaults: { ease: 'power2.out' }
  })

  // Logo reveal
  tl.from(elements.logo, {
    opacity: 0,
    scale: 0,
    duration: 0.8,
    ease: 'back.out(1.7)'
  })

  // Panels stagger in
  tl.from(elements.panels, {
    opacity: 0,
    x: -30,
    stagger: 0.1,
    duration: 0.5
  }, '-=0.3')

  // Status indicator
  tl.from(elements.status, {
    opacity: 0,
    y: 10,
    duration: 0.3
  }, '-=0.2')

  return tl
}

4.5 Scroll-Triggered Animation

<script setup lang="ts">
import { gsap } from 'gsap'
import { ScrollTrigger } from 'gsap/ScrollTrigger'

const sectionRef = ref<HTMLElement | null>(null)

onMounted(() => {
  if (!sectionRef.value) return

  gsap.from(sectionRef.value.querySelectorAll('.animate-item'), {
    scrollTrigger: {
      trigger: sectionRef.value,
      start: 'top 80%',
      end: 'bottom 20%',
      toggleActions: 'play none none reverse'
    },
    opacity: 0,
    y: 30,
    stagger: 0.1,
    duration: 0.5
  })
})

onUnmounted(() => {
  ScrollTrigger.getAll().forEach(trigger => trigger.kill())
})
</script>

5. Quality Standards

5.1 Performance

// ✅ GOOD - Use transforms for GPU acceleration
gsap.to(element, {
  x: 100,
  y: 50,
  rotation: 45,
  scale: 1.2
})

// ❌ BAD - Triggers layout recalculation
gsap.to(element, {
  left: 100,
  top: 50,
  width: '120%'
})

5.2 Accessibility

// ✅ Respect reduced motion
const prefersReducedMotion = window.matchMedia(
  '(prefers-reduced-motion: reduce)'
).matches

if (prefersReducedMotion) {
  gsap.set(element, { opacity: 1 })
} else {
  gsap.from(element, { opacity: 0, duration: 0.5 })
}

6. Performance Patterns

6.1 will-change Property Usage

// Good: Apply will-change before animation
const animatePanel = (element: HTMLElement) => {
  element.style.willChange = 'transform, opacity'

  gsap.to(element, {
    x: 100,
    opacity: 0.8,
    duration: 0.5,
    onComplete: () => {
      element.style.willChange = 'auto'
    }
  })
}

// Bad: Never removing will-change
const animatePanelBad = (element: HTMLElement) => {
  element.style.willChange = 'transform, opacity' // Memory leak!
  gsap.to(element, { x: 100, opacity: 0.8 })
}

6.2 Transform vs Layout Properties

// Good: Use transforms (GPU accelerated)
gsap.to(element, {
  x: 100,           // translateX
  y: 50,            // translateY
  scale: 1.2,       // scale
  rotation: 45,     // rotate
  opacity: 0.5      // opacity
})

// Bad: Layout-triggering properties (CPU, causes reflow)
gsap.to(element, {
  left: 100,        // Triggers layout
  top: 50,          // Triggers layout
  width: '120%',    // Triggers layout
  height: 200,      // Triggers layout
  margin: 10        // Triggers layout
})

6.3 Timeline Reuse

// Good: Reuse timeline instance
const timeline = gsap.timeline({ paused: true })
timeline
  .to(element, { opacity: 1, duration: 0.3 })
  .to(element, { y: -20, duration: 0.5 })

// Play/reverse as needed
const show = () => timeline.play()
const hide = () => timeline.reverse()

// Bad: Creating new timeline each time
const showBad = () => {
  gsap.timeline()
    .to(element, { opacity: 1, duration: 0.3 })
    .to(element, { y: -20, duration: 0.5 })
}

6.4 ScrollTrigger Batching

// Good: Batch ScrollTrigger animations
ScrollTrigger.batch('.animate-item', {
  onEnter: (elements) => {
    gsap.to(elements, {
      opacity: 1,
      y: 0,
      stagger: 0.1,
      overwrite: true
    })
  },
  onLeave: (elements) => {
    gsap.to(elements, {
      opacity: 0,
      y: -20,
      overwrite: true
    })
  }
})

// Bad: Individual ScrollTrigger per element
document.querySelectorAll('.animate-item').forEach(item => {
  gsap.to(item, {
    scrollTrigger: {
      trigger: item,
      start: 'top 80%'
    },
    opacity: 1,
    y: 0
  })
})

6.5 Lazy Initialization

// Good: Initialize animations only when needed
let panelAnimation: gsap.core.Timeline | null = null

const getPanelAnimation = () => {
  if (!panelAnimation) {
    panelAnimation = gsap.timeline({ paused: true })
      .from('.panel', { opacity: 0, y: 20 })
      .from('.panel-content', { opacity: 0, stagger: 0.1 })
  }
  return panelAnimation
}

const showPanel = () => getPanelAnimation().play()
const hidePanel = () => getPanelAnimation().reverse()

// Bad: Initialize all animations on mount
onMounted(() => {
  // Creates timeline even if never used
  const animation1 = gsap.timeline().to('.panel1', { x: 100 })
  const animation2 = gsap.timeline().to('.panel2', { y: 100 })
  const animation3 = gsap.timeline().to('.panel3', { scale: 1.2 })
})

7. Testing & Quality

7.1 Animation Testing

describe('Panel Animation', () => {
  it('cleans up on unmount', async () => {
    const wrapper = mount(HUDPanel)
    await wrapper.unmount()

    // No active GSAP animations should remain
    expect(gsap.globalTimeline.getChildren().length).toBe(0)
  })
})

8. Common Mistakes & Anti-Patterns

8.1 Critical Anti-Patterns

Never: Skip Cleanup

// ❌ MEMORY LEAK
onMounted(() => {
  gsap.to(element, { x: 100, duration: 1 })
})

// ✅ PROPER CLEANUP
let tween: gsap.core.Tween

onMounted(() => {
  tween = gsap.to(element, { x: 100, duration: 1 })
})

onUnmounted(() => {
  tween?.kill()
})

Never: Animate Layout Properties

// ❌ BAD - Causes layout thrashing
gsap.to(element, { width: 200, height: 100 })

// ✅ GOOD - Use transforms
gsap.to(element, { scaleX: 2, scaleY: 1 })

13. Pre-Implementation Checklist

Phase 1: Before Writing Code

• Write failing tests for animation behavior
• Define animation timing and easing requirements
• Identify elements that need will-change hints
• Plan cleanup strategy for all animations
• Check if reduced motion support is needed

Phase 2: During Implementation

• Use transforms/opacity only (no layout properties)
• Store animation references for cleanup
• Apply will-change before, remove after animation
• Use timelines for sequences
• Batch ScrollTrigger animations
• Implement lazy initialization for complex animations

Phase 3: Before Committing

• All tests pass (npm test -- --grep "Animation")
• All animations cleaned up on unmount
• Reduced motion preference respected
• No memory leaks (check with DevTools)
• 60fps maintained (test with performance monitor)
• ScrollTrigger instances properly killed

14. Summary

GSAP provides professional animations for JARVIS HUD:

1. Cleanup: Always kill animations on unmount
2. Performance: Use transforms and opacity only
3. Accessibility: Respect reduced motion preference
4. Organization: Use timelines for sequences

Remember: Every animation must be cleaned up to prevent memory leaks.

References:

• references/advanced-patterns.md - Complex animation patterns