Scroll Reveal Libraries

by freshtechbro1da73febff0cNo license1K starsListed Oct 8, 2026Updated Oct 8, 2026Repository updated 10 months ago

Simple scroll-triggered reveal animations using AOS (Animate On Scroll). Use this skill when building marketing pages, landing pages, or content-heavy sites requiring basic fade/slide effects without complex animation orchestration. Triggers on tasks involving scroll animations, scroll-triggered reveals, AOS, simple animations, or basic scroll effects. Alternative to GSAP ScrollTrigger and Locomotive Scroll for simpler use cases. Compare with motion-framer for React-specific animations.

Includes scriptsSoftware DevelopmentDesign & Creative
AI-generated overview

Guides use of the AOS library for simple scroll-triggered reveal animations on web pages.

What it does
This skill documents AOS (Animate On Scroll), a lightweight CSS-driven library for scroll-triggered fade, slide, zoom and flip effects. It covers installation via CDN or npm, global and per-element configuration, common page patterns, framework integration for React, Vue and Next.js, performance tuning and pitfalls. It also ships Python scripts that generate AOS HTML boilerplate and build AOS configuration.
When to use it
Use it when adding basic scroll reveal effects to marketing pages, landing pages, blogs or documentation sites. It suits quick prototypes where simple fade and slide animations are enough, rather than complex timelines or physics-based motion.
Requirements
Requires the AOS library (installed via npm/yarn or loaded from a CDN) and a web project using HTML, CSS and JavaScript; network access is needed for CDN loading. It ships two Python scripts, aos_generator.py and config_builder.py, so a Python runtime is needed to run them.

Scroll Reveal Libraries

Overview

This skill covers AOS (Animate On Scroll), a lightweight CSS-driven library for scroll-triggered animations. AOS excels at simple fade, slide, and zoom effects activated when elements enter the viewport.

Key Features:

  • Minimal Setup: Single JavaScript file + CSS
  • Data Attribute API: Configure animations in HTML
  • Performance: CSS-driven, GPU-accelerated animations
  • 50+ Built-in Animations: Fades, slides, zooms, flips
  • Framework Agnostic: Works with vanilla JS, React, Vue, etc.

When to Use:

  • Marketing/landing pages with simple scroll effects
  • Content-heavy sites (blogs, documentation)
  • Quick prototypes requiring scroll animations
  • Projects where GSAP/Framer Motion complexity isn't needed

When NOT to Use:

  • Complex animation timelines or orchestration → Use GSAP ScrollTrigger
  • Physics-based animations → Use React Spring or Framer Motion
  • Precise scroll-synced animations → Use GSAP ScrollTrigger
  • Heavy interactive animations → Use Framer Motion

Core Concepts

Installation

CDN (Quickest):

html
<head>  <link rel="stylesheet" href="https://unpkg.com/aos@next/dist/aos.css" /></head><body>  <!-- Content with data-aos attributes -->
  <script src="https://unpkg.com/aos@next/dist/aos.js"></script>  <script>    AOS.init();  </script></body>

NPM/Yarn (Recommended):

bash
npm install aos@next# oryarn add aos@next
javascript
import AOS from 'aos';import 'aos/dist/aos.css';
AOS.init();

Basic Usage

Apply animations using the data-aos attribute:

html
<!-- Fade in --><div data-aos="fade-in">Content</div>
<!-- Fade up --><div data-aos="fade-up">Content</div>
<!-- Slide from right --><div data-aos="slide-left">Content</div>
<!-- Zoom in --><div data-aos="zoom-in">Content</div>

Configuration Options

Global Configuration:

javascript
AOS.init({  // Animation settings  duration: 800,  // Animation duration (ms): 0-3000  delay: 0,       // Delay before animation (ms): 0-3000  offset: 120,    // Offset from trigger point (px)  easing: 'ease', // Easing function  once: false,    // Animate only once (true) or every time (false)  mirror: false,  // Animate out when scrolling past
  // Placement  anchorPlacement: 'top-bottom', // Which position triggers animation
  // Performance  disable: false,                // Disable on mobile/tablet  startEvent: 'DOMContentLoaded', // Initialization event  debounceDelay: 50,             // Window resize debounce  throttleDelay: 99              // Scroll throttle});

Per-Element Overrides:

html
<div  data-aos="fade-up"  data-aos-duration="1000"  data-aos-delay="200"  data-aos-offset="50"  data-aos-easing="ease-in-out"  data-aos-once="true"  data-aos-mirror="true"  data-aos-anchor-placement="center-bottom">  Custom configured element</div>

Common Patterns

1. Landing Page Hero Section

html
<section class="hero">  <!-- Staggered heading words -->  <h1    data-aos="fade-down"    data-aos-duration="800"  >    Welcome to the Future  </h1>
  <!-- Delayed subheading -->  <p    data-aos="fade-up"    data-aos-delay="200"    data-aos-duration="600"  >    Transform your ideas into reality  </p>
  <!-- CTA button -->  <button    data-aos="zoom-in"    data-aos-delay="400"    data-aos-duration="500"  >    Get Started  </button></section>

2. Feature Cards Grid

html
<div class="features-grid">  <!-- Stagger cards with increasing delays -->  <div    class="feature-card"    data-aos="fade-up"    data-aos-duration="600"    data-aos-delay="0"  >    <h3>Feature 1</h3>    <p>Description...</p>  </div>
  <div    class="feature-card"    data-aos="fade-up"    data-aos-duration="600"    data-aos-delay="100"  >    <h3>Feature 2</h3>    <p>Description...</p>  </div>
  <div    class="feature-card"    data-aos="fade-up"    data-aos-duration="600"    data-aos-delay="200"  >    <h3>Feature 3</h3>    <p>Description...</p>  </div></div>

3. Alternating Content Sections

html
<!-- Content from left --><div class="section">  <div    class="content"    data-aos="slide-right"    data-aos-duration="800"  >    <h2>Section Title</h2>    <p>Content slides in from left...</p>  </div>  <img    src="image1.jpg"    data-aos="fade-left"    data-aos-delay="200"  /></div>
<!-- Content from right --><div class="section reverse">  <img    src="image2.jpg"    data-aos="fade-right"  />  <div    class="content"    data-aos="slide-left"    data-aos-duration="800"    data-aos-delay="200"  >    <h2>Section Title</h2>    <p>Content slides in from right...</p>  </div></div>

4. Scroll-Triggered Testimonials

html
<div class="testimonials">  <div    class="testimonial"    data-aos="zoom-in"    data-aos-duration="500"  >    <blockquote>"Amazing product!"</blockquote>    <cite>- John Doe</cite>  </div>
  <div    class="testimonial"    data-aos="zoom-in"    data-aos-duration="500"    data-aos-delay="100"  >    <blockquote>"Exceeded expectations"</blockquote>    <cite>- Jane Smith</cite>  </div></div>

5. Custom Anchor Triggers

Trigger animations based on a different element's scroll position:

html
<!-- Fixed sidebar animates based on main content scroll --><div class="main-content">  <div id="trigger-point" data-aos-id="sidebar-trigger">    <!-- Content -->  </div></div>
<aside  class="sidebar"  data-aos="fade-left"  data-aos-anchor="#trigger-point">  Sidebar content</aside>

6. Sequential Animation Chain

html
<div class="animation-sequence">  <!-- Step 1: Heading -->  <h2    data-aos="fade-down"    data-aos-duration="600"    data-aos-delay="0"  >    Our Process  </h2>
  <!-- Step 2: Description -->  <p    data-aos="fade-up"    data-aos-duration="600"    data-aos-delay="200"  >    Follow these simple steps  </p>
  <!-- Step 3-5: Process cards -->  <div    class="process-step"    data-aos="flip-left"    data-aos-delay="400"  >    Step 1  </div>
  <div    class="process-step"    data-aos="flip-left"    data-aos-delay="600"  >    Step 2  </div>
  <div    class="process-step"    data-aos="flip-left"    data-aos-delay="800"  >    Step 3  </div></div>

7. Image Gallery with Zoom Effects

html
<div class="gallery">  <img    src="photo1.jpg"    data-aos="zoom-in-up"    data-aos-duration="800"  />  <img    src="photo2.jpg"    data-aos="zoom-in-up"    data-aos-duration="800"    data-aos-delay="100"  />  <img    src="photo3.jpg"    data-aos="zoom-in-up"    data-aos-duration="800"    data-aos-delay="200"  /></div>

Integration Patterns

React Integration

Basic Setup:

jsx
import { useEffect } from 'react';import AOS from 'aos';import 'aos/dist/aos.css';
function App() {  useEffect(() => {    AOS.init({      duration: 800,      once: true,      offset: 100    });  }, []);
  return (    <div>      <h1 data-aos="fade-down">Welcome</h1>      <p data-aos="fade-up">Content here</p>    </div>  );}

Refreshing on Route Changes:

jsx
import { useEffect } from 'react';import { useLocation } from 'react-router-dom';import AOS from 'aos';
function App() {  const location = useLocation();
  useEffect(() => {    AOS.init({ duration: 800 });  }, []);
  // Refresh AOS on route change  useEffect(() => {    AOS.refresh();  }, [location]);
  return <Routes>{/* routes */}</Routes>;}

Dynamic Content Updates:

jsx
import { useState, useEffect } from 'react';import AOS from 'aos';
function DynamicList() {  const [items, setItems] = useState([]);
  useEffect(() => {    AOS.init();  }, []);
  const addItem = () => {    setItems([...items, { id: Date.now(), text: 'New Item' }]);
    // Refresh AOS to detect new elements    setTimeout(() => AOS.refresh(), 50);  };
  return (    <div>      <button onClick={addItem}>Add Item</button>      <ul>        {items.map((item) => (          <li key={item.id} data-aos="fade-in">            {item.text}          </li>        ))}      </ul>    </div>  );}

Component Wrapper Pattern:

jsx
import AOS from 'aos';import 'aos/dist/aos.css';
function AnimatedSection({ children, animation = "fade-up", delay = 0, ...props }) {  return (    <div      data-aos={animation}      data-aos-delay={delay}      {...props}    >      {children}    </div>  );}
// Usage<AnimatedSection animation="slide-right" delay={200}>  <h2>Animated Content</h2></AnimatedSection>

Vue.js Integration

vue
<template>  <div>    <h1 data-aos="fade-down">Vue + AOS</h1>    <div      v-for="(item, index) in items"      :key="item.id"      data-aos="fade-up"      :data-aos-delay="index * 100"    >      {{ item.text }}    </div>  </div></template>
<script>import AOS from 'aos';import 'aos/dist/aos.css';
export default {  mounted() {    AOS.init({ duration: 800 });  },  updated() {    // Refresh when component updates    this.$nextTick(() => {      AOS.refresh();    });  },  data() {    return {      items: [/*...*/]    };  }};</script>

Next.js Integration

jsx
// pages/_app.jsimport { useEffect } from 'react';import AOS from 'aos';import 'aos/dist/aos.css';
function MyApp({ Component, pageProps }) {  useEffect(() => {    AOS.init({      duration: 800,      once: true    });  }, []);
  return <Component {...pageProps} />;}
export default MyApp;
jsx
// pages/index.jsexport default function Home() {  return (    <main>      <h1 data-aos="fade-down">Next.js + AOS</h1>      <p data-aos="fade-up">Server-side rendered content with animations</p>    </main>  );}

Performance Optimization

1. Disable on Mobile Devices

javascript
AOS.init({  disable: 'mobile', // Disable on mobile  // Or use function for custom logic  disable: function() {    return window.innerWidth < 768;  }});

2. Use Once for Better Performance

javascript
AOS.init({  once: true, // Animate only once (better performance)  mirror: false // Don't animate out});

3. Optimize Throttle and Debounce

javascript
AOS.init({  throttleDelay: 99,  // Scroll event throttle (default)  debounceDelay: 50   // Resize event debounce (default)});

4. Disable Mutation Observer for Static Content

javascript
AOS.init({  disableMutationObserver: true // Disable for fully static content});

5. Reduce Animation Complexity

html
<!-- Simpler animations perform better --><div data-aos="fade-in">Simple fade</div>
<!-- Complex animations may cause jank --><div data-aos="flip-left">Complex flip</div>

6. Use RequestIdleCallback for Initialization

javascript
if ('requestIdleCallback' in window) {  requestIdleCallback(() => {    AOS.init({ duration: 800 });  });} else {  AOS.init({ duration: 800 });}

Common Pitfalls

1. Forgetting to Refresh After DOM Changes

Problem: New elements don't animate after being added dynamically.

Solution: Call AOS.refresh() or AOS.refreshHard():

javascript
// After adding elements to DOMconst newElement = document.createElement('div');newElement.setAttribute('data-aos', 'fade-in');container.appendChild(newElement);
// Refresh AOSAOS.refresh(); // Recalculate positions// orAOS.refreshHard(); // Reinitialize completely

2. Animations Not Working in React

Problem: AOS doesn't detect elements on first render or route changes.

Solution: Initialize in useEffect and refresh on route/content changes:

jsx
useEffect(() => {  AOS.init();  return () => AOS.refresh(); // Cleanup}, []);
useEffect(() => {  AOS.refresh(); // Refresh on route change}, [location.pathname]);

3. Scroll Performance Issues

Problem: Page scrolling feels janky with many animated elements.

Solution: Reduce animated elements and use once: true:

javascript
AOS.init({  once: true, // Animate only once  disable: window.innerWidth < 768 // Disable on mobile});

4. CSS Conflicts

Problem: Custom CSS interferes with AOS animations.

Solution: Use more specific selectors and avoid !important:

css
/* Bad: Conflicts with AOS */div {  opacity: 1 !important;}
/* Good: Specific selector */.my-content > div {  /* styles */}

5. Anchor Placement Confusion

Problem: Animations trigger at unexpected scroll positions.

Solution: Understand anchor placement options:

javascript
// Triggers when element's top hits viewport bottomdata-aos-anchor-placement="top-bottom"
// Triggers when element's center hits viewport centerdata-aos-anchor-placement="center-center"
// Triggers when element's bottom hits viewport topdata-aos-anchor-placement="bottom-top"

6. Duration/Delay Limits

Problem: Values above 3000ms don't work.

Solution: Add custom CSS for extended durations:

css
body[data-aos-duration='4000'] [data-aos],[data-aos][data-aos][data-aos-duration='4000'] {  transition-duration: 4000ms;}
html
<div data-aos="fade-in" data-aos-duration="4000">  Long animation</div>

Built-in Animations

Fade Animations

  • fade-in - Simple fade in
  • fade-up - Fade in from bottom
  • fade-down - Fade in from top
  • fade-left - Fade in from right
  • fade-right - Fade in from left
  • fade-up-right - Diagonal fade
  • fade-up-left - Diagonal fade
  • fade-down-right - Diagonal fade
  • fade-down-left - Diagonal fade

Slide Animations

  • slide-up - Slide from bottom
  • slide-down - Slide from top
  • slide-left - Slide from right
  • slide-right - Slide from left

Zoom Animations

  • zoom-in - Zoom in
  • zoom-in-up - Zoom in from bottom
  • zoom-in-down - Zoom in from top
  • zoom-in-left - Zoom in from right
  • zoom-in-right - Zoom in from left
  • zoom-out - Zoom out
  • zoom-out-up - Zoom out to top
  • zoom-out-down - Zoom out to bottom
  • zoom-out-left - Zoom out to left
  • zoom-out-right - Zoom out to right

Flip Animations

  • flip-up - Flip from bottom
  • flip-down - Flip from top
  • flip-left - Flip from right
  • flip-right - Flip from left

Custom Animations

Create custom animations with CSS:

css
[data-aos="custom-slide-bounce"] {  opacity: 0;  transform: translateY(100px);  transition-property: transform, opacity;}
[data-aos="custom-slide-bounce"].aos-animate {  opacity: 1;  transform: translateY(0);  animation: bounce 0.5s;}
@keyframes bounce {  0%, 20%, 50%, 80%, 100% {    transform: translateY(0);  }  40% {    transform: translateY(-10px);  }  60% {    transform: translateY(-5px);  }}
html
<div data-aos="custom-slide-bounce">  Custom animation</div>

Comparison with Alternatives

AOS vs GSAP ScrollTrigger

FeatureAOSGSAP ScrollTrigger
ComplexitySimple, data-attribute basedAdvanced, JavaScript API
Use CaseSimple revealsComplex timelines
File Size~13KB~27KB (GSAP) + ScrollTrigger
PerformanceCSS-drivenJavaScript-driven
Learning CurveMinutesHours
CustomizationLimitedExtensive
Best ForMarketing pagesInteractive experiences

Use AOS when:

  • Simple fade/slide/zoom effects
  • Quick implementation needed
  • Minimal JavaScript preferred
  • Basic scroll reveals sufficient

Use GSAP ScrollTrigger when:

  • Complex animation sequences
  • Precise scroll-synced animations
  • Timeline orchestration needed
  • Advanced easing/physics required

Resources

Official Documentation

Key Scripts

  • scripts/aos_generator.py - Generate AOS HTML boilerplate
  • scripts/config_builder.py - Build AOS configuration

References

  • references/aos_api.md - Complete AOS API reference
  • references/animation_catalog.md - All built-in animations with demos
  • references/integration_patterns.md - Framework integration guides

Starter Assets

  • assets/starter_aos/ - Complete AOS starter template
  • assets/examples/ - Production-ready patterns

Related Skills

  • gsap-scrolltrigger: For complex scroll-driven animations
  • motion-framer: For React-specific animations with physics
  • locomotive-scroll: For smooth scrolling with parallax
  • animated-component-libraries: For pre-built animated React components

Source and attribution

Source:freshtechbro/claudedesignskillsin.claude/skills/scroll-reveal-librariesat commit1da73fe

License: No license

Content belongs to its original authors. SourceWeft indexes it from a public repository.

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