gsap-scrolltrigger

GSAP ScrollTrigger

Scroll-driven animations and interactions.

Quick Start

npm install gsap

import gsap from 'gsap';
import { ScrollTrigger } from 'gsap/ScrollTrigger';

gsap.registerPlugin(ScrollTrigger);

gsap.to('.box', {
  x: 500,
  scrollTrigger: {
    trigger: '.box',
    start: 'top center',
    end: 'bottom center',
    scrub: true
  }
});

Core Concepts

Basic ScrollTrigger

gsap.to('.element', {
  x: 200,
  scrollTrigger: {
    trigger: '.element',  // Element that triggers the animation
    start: 'top center',  // When trigger hits viewport center
    end: 'bottom center', // When trigger leaves viewport center
    toggleActions: 'play pause resume reset'
  }
});

Start/End Positions

// Format: "trigger-position viewport-position"
start: 'top center'      // Trigger's top hits viewport center
start: 'top 80%'         // Trigger's top hits 80% down viewport
start: 'center center'   // Trigger's center hits viewport center
start: 'bottom top'      // Trigger's bottom hits viewport top
start: 'top top+=100'    // Trigger's top hits 100px below viewport top

Position Reference

Value	Description
top	Top edge
center	Center
bottom	Bottom edge
80%	80% from top
+=100	Plus 100 pixels
-=50	Minus 50 pixels

Scrub Animations

Basic Scrub

// Animation progress tied to scroll position
gsap.to('.progress-bar', {
  scaleX: 1,
  scrollTrigger: {
    trigger: '.content',
    start: 'top top',
    end: 'bottom bottom',
    scrub: true  // Directly linked to scroll
  }
});

Smooth Scrub

gsap.to('.element', {
  x: 500,
  scrollTrigger: {
    trigger: '.section',
    scrub: 1,    // 1 second smoothing
    // scrub: 0.5  // 0.5 second smoothing
    // scrub: 2    // 2 second smoothing (laggy feel)
  }
});

Scrub with Timeline

const tl = gsap.timeline({
  scrollTrigger: {
    trigger: '.container',
    start: 'top top',
    end: '+=3000',  // Scroll distance
    scrub: 1,
    pin: true
  }
});

tl.to('.step1', { opacity: 1 })
  .to('.step2', { opacity: 1 })
  .to('.step3', { opacity: 1 });