/locomotive-scroll

name: locomotive-scroll
description: Comprehensive skill for Locomotive Scroll smooth scrolling library with parallax effects, viewport detection, and scroll-driven animations. Use this skill when implementing smooth scrolling experiences, creating parallax effects, building scroll-triggered animations, or developing immersive scrolling websites. Triggers on tasks involving Locomotive Scroll, smooth scrolling, parallax, scroll detection, scroll events, sticky elements, horizontal scrolling, or GSAP ScrollTrigger integration. Integrates with GSAP for advanced scroll-driven animations.

Locomotive Scroll

Comprehensive guide for implementing smooth scrolling, parallax effects, and scroll-driven animations using Locomotive Scroll.

Overview

Locomotive Scroll is a JavaScript library that provides:

• **Smooth scrolling**: Hardware-accelerated smooth scroll with customizable easing
• **Parallax effects**: Element-level speed control for depth
• **Viewport detection**: Track when elements enter/exit viewport
• **Scroll events**: Monitor scroll progress for animation synchronization
• **Sticky elements**: Pin elements within defined boundaries
• **Horizontal scrolling**: Support for horizontal scroll layouts

**When to use Locomotive Scroll:**

• Building immersive landing pages with parallax
• Creating smooth, Apple-style scroll experiences
• Implementing scroll-triggered animations
• Developing narrative/storytelling websites
• Adding depth and motion to long-form content

**Trade-offs:**

• Scroll-hijacking can impact accessibility (provide disable option)
• Performance overhead on low-end devices (detect and disable)
• Mobile touch scrolling feels different (test extensively)
• Fixed positioning requires workarounds

Installation

npm install locomotive-scroll

// ES6
import LocomotiveScroll from 'locomotive-scroll';
import 'locomotive-scroll/dist/locomotive-scroll.css';

// Or via CDN
<link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/locomotive-scroll/dist/locomotive-scroll.min.css">
<script src="https://cdn.jsdelivr.net/npm/locomotive-scroll/dist/locomotive-scroll.min.js"></script>

Core Concepts

1. HTML Structure

Every Locomotive Scroll implementation requires specific data attributes:

<!-- Scroll container (required) -->
<div data-scroll-container>

  <!-- Scroll sections (optional, improves performance) -->
  <div data-scroll-section>

    <!-- Tracked elements -->
    <h1 data-scroll>Basic detection</h1>

    <!-- Parallax element -->
    <div data-scroll data-scroll-speed="2">
      Moves faster than scroll
    </div>

    <!-- Sticky element -->
    <div data-scroll data-scroll-sticky>
      Sticks within section
    </div>

    <!-- Element with ID for tracking -->
    <div data-scroll data-scroll-id="hero">
      Accessible via JavaScript
    </div>

    <!-- Call event trigger -->
    <div data-scroll data-scroll-call="fadeIn">
      Triggers custom event
    </div>

  </div>
</div>

2. Initialization

const scroll = new LocomotiveScroll({
  el: document.querySelector('[data-scroll-container]'),
  smooth: true,
  lerp: 0.1,        // Smoothness (0-1, lower = smoother)
  multiplier: 1,    // Speed multiplier
  class: 'is-inview', // Class added to visible elements
  repeat: false,    // Repeat in-view detection
  offset: [0, 0]    // Global trigger offset [bottom, top]
});

3. Data Attributes

| Attribute | Purpose | Example | |-----------|---------|---------| | `data-scroll` | Enable detection | `data-scroll` | | `data-scroll-speed` | Parallax speed | `data-scroll-speed="2"` | | `data-scroll-direction` | Parallax axis | `data-scroll-direction="horizontal"` | | `data-scroll-sticky` | Sticky positioning | `data-scroll-sticky` | | `data-scroll-target` | Sticky boundary | `data-scroll-target="#section"` | | `data-scroll-offset` | Trigger offset | `data-scroll-offset="20%"` | | `data-scroll-repeat` | Repeat detection | `data-scroll-repeat` | | `data-scroll-call` | Event trigger | `data-scroll-call="myFunction"` | | `data-scroll-id` | Unique identifier | `data-scroll-id="hero"` | | `data-scroll-class` | Custom class | `data-scroll-class="is-visible"` |

Common Patterns

1. Basic Smooth Scrolling

import LocomotiveScroll from 'locomotive-scroll';

const scroll = new LocomotiveScroll({
  el: document.querySelector('[data-scroll-container]'),
  smooth: true
});

<div data-scroll-container>
  <div data-scroll-section>
    <h1>Smooth scrolling enabled</h1>
  </div>
</div>

2. Parallax Effects

<!-- Slow parallax -->
<div data-scroll data-scroll-speed="0.5">
  Moves slower than scroll (background effect)
</div>

<!-- Fast parallax -->
<div data-scroll data-scroll-speed="3">
  Moves faster than scroll (foreground effect)
</div>

<!-- Reverse parallax -->
<div data-scroll data-scroll-speed="-2">
  Moves in opposite direction
</div>

<!-- Horizontal parallax -->
<div data-scroll data-scroll-speed="2" data-scroll-direction="horizontal">
  Moves horizontally
</div>

3. Viewport Detection and Callbacks

// Track scroll progress
scroll.on('scroll', (args) => {
  console.log(args.scroll.y); // Current scroll position
  console.log(args.speed);    // Scroll speed
  console.log(args.direction); // Scroll direction

  // Access specific element progress
  if (args.currentElements['hero']) {
    const progress = args.currentElements['hero'].progress;
    console.log(`Hero progress: ${progress}`); // 0 to 1
  }
});

// Call events
scroll.on('call', (value, way, obj) => {
  console.log(`Event triggered: ${value}`);
  // value = data-scroll-call attribute value
  // way = 'enter' or 'exit'
  // obj = {id, el}
});

<div data-scroll data-scroll-id="hero">Hero section</div>
<div data-scroll data-scroll-call="playVideo">Video section</div>

4. Sticky Elements

<!-- Stick within parent section -->
<div data-scroll-s