Animejs

Anime.js

Lightweight JavaScript animation library with powerful timeline and stagger capabilities for web animations.

Overview

Anime.js (pronounced "Anime JS") is a versatile animation engine that works with DOM elements, CSS properties, SVG attributes, and JavaScript objects. Unlike React-specific libraries, Anime.js works with vanilla JavaScript and any framework.

When to use this skill:

• Timeline-based animation sequences with precise choreography
• Staggered animations across multiple elements
• SVG path morphing and drawing animations
• Keyframe animations with percentage-based timing
• Framework-agnostic animation (works with React, Vue, vanilla JS)
• Complex easing functions (spring, steps, cubic-bezier)

Core features:

• Timeline sequencing with relative positioning
• Powerful stagger utilities (grid, from center, easing)
• SVG morphing and path animations
• Built-in spring physics easing
• Keyframe support with flexible timing
• Small bundle size (~9KB gzipped)

Core Concepts

Basic Animation

The anime() function creates animations:

import anime from 'animejs'

anime({
  targets: '.element',
  translateX: 250,
  rotate: '1turn',
  duration: 800,
  easing: 'easeInOutQuad'
})

Targets

Multiple ways to specify animation targets:

// CSS selector
anime({ targets: '.box' })

// DOM elements
anime({ targets: document.querySelectorAll('.box') })

// Array of elements
anime({ targets: [el1, el2, el3] })

// JavaScript object
const obj = { x: 0 }
anime({ targets: obj, x: 100 })

Animatable Properties

CSS Properties:

anime({
  targets: '.element',
  translateX: 250,
  scale: 2,
  opacity: 0.5,
  backgroundColor: '#FFF'
})

CSS Transforms (Individual):

anime({
  targets: '.element',
  translateX: 250,   // Individual transform
  rotate: '1turn',   // Not 'transform: rotate()'
  scale: 2
})

SVG Attributes:

anime({
  targets: 'path',
  d: 'M10 80 Q 77.5 10, 145 80', // Path morphing
  fill: '#FF0000',
  strokeDashoffset: [anime.setDashoffset, 0] // Line drawing
})

JavaScript Objects:

const obj = { value: 0 }
anime({
  targets: obj,
  value: 100,
  round: 1,
  update: () => console.log(obj.value)
})

Timeline

Create complex sequences with precise control:

const timeline = anime.timeline({
  duration: 750,
  easing: 'easeOutExpo'
})

timeline
  .add({
    targets: '.box1',
    translateX: 250
  })
  .add({
    targets: '.box2',
    translateX: 250
  }, '-=500') // Start 500ms before previous animation ends
  .add({
    targets: '.box3',
    translateX: 250
  }, '+=200') // Start 200ms after previous animation ends

Common Patterns

1. Stagger Animation (Sequential Reveal)

anime({
  targets: '.stagger-element',
  translateY: [100, 0],
  opacity: [0, 1],
  delay: anime.stagger(100), // Increase delay by 100ms
  easing: 'easeOutQuad',
  duration: 600
})

2. Stagger from Center

anime({
  targets: '.grid-item',
  scale: [0, 1],
  delay: anime.stagger(50, {
    grid: [14, 5],
    from: 'center', // Also: 'first', 'last', index, [x, y]
    axis: 'x'       // Also: 'y', null
  }),
  easing: 'easeOutQuad'
})

3. SVG Line Drawing

anime({
  targets: 'path',
  strokeDashoffset: [anime.setDashoffset, 0],
  easing: 'easeInOutQuad',
  duration: 2000,
  delay: (el, i) => i * 250
})

4. SVG Morphing

anime({
  targets: '#morphing-path',
  d: [
    { value: 'M10 80 Q 77.5 10, 145 80' }, // Start shape
    { value: 'M10 80 Q 77.5 150, 145 80' }  // End shape
  ],
  duration: 2000,
  easing: 'easeInOutQuad',
  loop: true,
  direction: 'alternate'
})

5. Timeline Sequence

const tl = anime.timeline({
  easing: 'easeOutExpo',
  duration: 750
})

tl.add({
  targets: '.title',
  translateY: [-50, 0],
  opacity: [0, 1]
})
.add({
  targets: '.subtitle',
  translateY: [-30, 0],
  opacity: [0, 1]
}, '-=500')
.add({
  targets: '.button',
  scale: [0, 1],
  opacity: [0, 1]
}, '-=300')

6. Keyframe Animation

anime({
  targets: '.element',
  keyframes: [
    { translateX: 100 },
    { translateY: 100 },
    { translateX: 0 },
    { translateY: 0 }
  ],
  duration: 4000,
  easing: 'easeInOutQuad',
  loop: true
})

7. Scroll-Triggered Animation

const animation = anime({
  targets: '.scroll-element',
  translateY: [100, 0],
  opacity: [0, 1],
  easing: 'easeOutQuad',
  autoplay: false
})

window.addEventListener('scroll', () => {
  const scrollPercent = window.scrollY / (document.body.scrollHeight - window.innerHeight)
  animation.seek(animation.duration * scrollPercent)
})

Integration Patterns

With React

import { useEffect, useRef } from 'react'
import anime from 'animejs'

function AnimatedComponent() {
  const ref = useRef(null)

  useEffect(() => {
    const animation = anime({
      targets: ref.current,
      translateX: 250,
      duration: 800,
      easing: 'easeInOutQuad'
    })

    return () => animation.pause()
  }, [])

  return <div ref={ref}>Animated</div>
}

With Vue

export default {
  mounted() {
    anime({
      targets: this.$el,
      translateX: 250,
      duration: 800
    })
  }
}

Path Following Animation

const path = anime.path('#motion-path')

anime({
  targets: '.element',
  translateX: path('x'),
  translateY: path('y'),
  rotate: path('angle'),
  easing: 'linear',
  duration: 2000,
  loop: true
})

Advanced Techniques

Spring Easing

anime({
  targets: '.element',
  translateX: 250,
  easing: 'spring(1, 80, 10, 0)', // mass, stiffness, damping, velocity
  duration: 2000
})

Steps Easing

anime({
  targets: '.element',
  translateX: 250,
  easing: 'steps(5)',
  duration: 1000
})

Custom Bezier

anime({
  targets: '.element',
  translateX: 250,
  easing: 'cubicBezier(.5, .05, .1, .3)',
  duration: 1000
})

Direction and Loop

anime({
  targets: '.element',
  translateX: 250,
  direction: 'alternate', // 'normal', 'reverse', 'alternate'
  loop: true,             // or number of iterations
  easing: 'easeInOutQuad'
})

Playback Control

const animation = anime({
  targets: '.element',
  translateX: 250,
  autoplay: false
})

animation.play()
animation.pause()
animation.restart()
animation.reverse()
animation.seek(500) // Seek to 500ms

Performance Optimization

Use Transform and Opacity

// ✅ Good: GPU-accelerated
anime({
  targets: '.element',
  translateX: 250,
  opacity: 0.5
})

// ❌ Avoid: Triggers layout
anime({
  targets: '.element',
  left: '250px',
  width: '500px'
})

Batch Similar Animations

// ✅ Single animation for multiple targets
anime({
  targets: '.multiple-elements',
  translateX: 250
})

// ❌ Avoid: Multiple separate animations
elements.forEach(el => {
  anime({ targets: el, translateX: 250 })
})

Use will-change for Complex Animations

.animated-element {
  will-change: transform, opacity;
}

Disable autoplay for Scroll Animations

const animation = anime({
  targets: '.element',
  translateX: 250,
  autoplay: false // Control manually
})

Common Pitfalls

1. Forgetting Unit Types

// ❌ Wrong: No unit
anime({ targets: '.element', width: 200 })

// ✅ Correct: Include unit
anime({ targets: '.element', width: '200px' })

2. Using CSS transform Property Directly

// ❌ Wrong: Can't animate transform string
anime({ targets: '.element', transform: 'translateX(250px)' })

// ✅ Correct: Individual transform properties
anime({ targets: '.element', translateX: 250 })

3. Not Handling Animation Cleanup

// ❌ Wrong: Animation continues after unmount
useEffect(() => {