🎠 Carousel Pilot

A zero-dependency, framework-agnostic web component that enhances your existing scrollable content with carousel functionality. The Carousel is yours, but Carousel Pilot handles navigation (prev/next), active state, autoplay, infinite loop and scroll tracking.

Why?

Carousels are hard. You either use a heavy JS-based library or you gotta build things on your own. CSS scroll snapping has made it easier to build lightweight carousels, but some functionality like having the slides loop around are still heavily dependent on JS, and notably a pain to implement.

With Carousel Pilot you can have the both of best worlds: the scrolling and snapping is still handled by your CSS, responsive and reliable, but, if JavaScript is available, you can have Carousel Pilot jump in and add the extra goodies it provides, including a smooth infinite loop experience.

The cost? 17.7kB (gzipped). It's not the most lightweight option out there, but hopefully it's the most straightforward one to use.

How it works

Carousel Pilot is a custom element (<carousel-pilot>) that wraps your existing scrollable track. It doesn't impose any layout or styles — you style the track and slides however you want (flexbox, CSS scroll snap, etc.) and Carousel Pilot wires up the behavior.

It is built with Svelte 5, but works with any framework or no framework at all.

Installation

npm install carousel-pilot

Usage

With a bundler (Vite, Webpack, Rollup, etc.)

Import once anywhere in your app — this registers the custom element globally:

import 'carousel-pilot';

In a Svelte project

import 'carousel-pilot';
// or, to use the Svelte component directly:
import { CarouselPilot } from 'carousel-pilot';

Via CDN / plain HTML

<script type="module" src="https://unpkg.com/carousel-pilot/dist/carousel-pilot.js"></script>

Basic example

The only required piece is a scrollable track element marked with data-carousel-track. Everything else is optional.

<carousel-pilot>
  <ul data-carousel-track>
    <li>Slide 1</li>
    <li>Slide 2</li>
    <li>Slide 3</li>
  </ul>

  <!-- Optional navigation -->
  <button data-carousel-prev>Prev</button>
  <span>Slide <span data-carousel-currentIndex>1</span> of 3</span>
  <button data-carousel-next>Next</button>
</carousel-pilot>

You are responsible for the track's CSS layout. A typical setup with CSS scroll snap:

[data-carousel-track] {
  display: flex;
  gap: 1rem;
  overflow: auto;
  scroll-snap-type: x mandatory;
}

[data-carousel-track] > li {
  flex: 0 0 300px;
  scroll-snap-align: start;
}

Slot conventions

Mark elements inside <carousel-pilot> with these data attributes to connect them:

Attribute	Role
data-carousel-track	The scrollable slide container (required)
data-carousel-prev	Button to scroll to the previous slide
data-carousel-next	Button to scroll to the next slide
data-carousel-indicator	Repeated indicator elements (e.g. dots); the active one gets an active class
data-carousel-currentIndex	Element whose text content is updated with the current slide number (1-based)

Props

Selectors

These props accept a CSS selector string. Each one falls back to its corresponding data-* attribute if left empty.

Prop	Default fallback	Description
track	[data-carousel-track]	The scrollable slide container. Required.
prev	[data-carousel-prev]	Button to scroll to the previous slide.
next	[data-carousel-next]	Button to scroll to the next slide.
indicators	[data-carousel-indicator]	Repeated indicator elements (e.g. dots). The active one receives an active class.
current	[data-carousel-currentIndex]	Element whose text content is set to the current slide number (1-based).

Behavior

Prop	Type	Default	Description
centered	boolean	false	Centers the active slide in the track. Use scroll-snap-align: center on slides when enabled.
scrollAmount	'slide' | 'page'	'slide'	How far prev/next scroll. 'slide' uses the active slide's width; 'page' uses the track's full width.

CSS injection

Prop	Type	Default	Description
addSpacers	boolean	true	Injects invisible spacer elements so the first and last slides can be scrolled flush to the edge (or center when centered is on).
showScrollShadow	boolean	false	Injects a CSS scroll shadow on the track to hint that more content is scrollable.
hideScrollbar	boolean	false	Hides the track's scrollbar via injected CSS.

Autoplay

Prop	Type	Default	Description
autoplay	boolean	false	Automatically advances slides on an interval. Pauses on hover, stops permanently on manual scroll or prev/next interaction.
autoplayDelay	number	5000	Interval in milliseconds between autoplay advances.

Loop

Prop	Type	Default	Description
loop	boolean	false	Enables infinite looping by cloning slides on each side of the track.
dedupeHeadings	boolean	true	Replaces heading elements inside cloned slides with <div>s to prevent duplicate headings in the document outline.
headingClasses	string	'h1, h2, h3, h4, h5, h6'	Comma-separated class names applied to heading replacements in clones (index 0 → h1 class, 1 → h2, etc.).

JavaScript API

const carousel = document.querySelector('carousel-pilot');

carousel.scrollToIndex(2);       // scroll to a specific slide (0-based)
carousel.scrollNext();           // scroll forward one slide
carousel.scrollPrev();           // scroll backward one slide

Events

carousel.addEventListener('slide-change', (e) => {
  console.log(e.detail.index); // 0-based index of the new active slide
  console.log(e.detail.total); // total number of slides
});

carousel.addEventListener('autoplay-started', () => { /* ... */ });
carousel.addEventListener('autoplay-stopped', (e) => {
  console.log(e.detail.paused); // true = paused (hovering), false = stopped permanently
});

Development

The project uses Storybook for local development. Example components live in src/lib/examples/.

npm install
npm run storybook

Storybook will start at http://localhost:6006.

Building & publishing

Build both the Svelte library distribution and the standalone bundle:

npm run prepack

This runs svelte-package (for Svelte users) and a Vite library build (for everyone else), then validates the output with publint. Both outputs land in dist/.

Publish to npm:

npm publish

Make sure you've updated the version field in package.json before publishing.