Scroll Snap Slider

Mostly CSS slider with great performance.

demo | docs

Table of Contents

• Premise
• Sizes
• Restrictions
• Installing
• Usage
  • Markup
  • CSS
  • Additional Styles
  • JavaScript
• API
• Events
• Public Properties
• Support
• Contributing

Features

• Native touch integration (draggable)
• Native scroll integration (any peripheral — if it can scroll, it can use this slider)
• Full HTML slides (any content possible)
• Usable with native DOM methods like scrollIntoView()

Premise

This library is an opinionated minimal implementation of a common feature across many websites. To keep it small, there are not many fancy features and there is almost no error handling.

However, with a clear API and the use of a ES6 class, it can provide a useful base for custom extensions.

What this module contains:

• Example markup for a scroll-snap slider
• CSS default styling for a scroll-snap slider without scrollbars
• ES6 class to slightly enhance functionality
• ES6 class plugins for loop, autoplay, and desktop/mouse draggable features
• TypeScript Typings

Sizes

Here are the sizes of individual modules, using terser and gzip with default options. The size increase at bundlephobia between v2 and v3 is due to the entrypoint changing from 'ScrollSnapSlider' to 'index'.

Item	minified (terser)	minified + gzipped
complete exports	8462 B	2140 B

Restrictions

This library only handles sliders on the X-axis.

For more "fully-featured" implementations, go to:

• Nick Piscitelli's Glider.js
• Tanner Hodges' snap-slider

Installing

npm install scroll-snap-slider 

yarn add scroll-snap-slider
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Usage

The class provided in this package augments a slider with a few events and methods.

Markup

You can add whatever markup inside the slides.

<ul class="scroll-snap-slider">
  <li class="scroll-snap-slide">
    <img
      alt=""
      src="https://picsum.photos/id/1011/400/300"
    />
  </li>
  <li class="scroll-snap-slide">
    <img
      alt=""
      src="https://picsum.photos/id/1018/400/300"
    />
  </li>
</ul>
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CSS

@import 'scroll-snap-slider';
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Additional Styles

Prevents page navigation on horizontal scrolling, i.E. on macOS. [Support tables]

.scroll-snap-slider {
  overscroll-behavior-x: none;
  overscroll-behavior-y: auto;
}
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Prevents scrolling past elements in the slider: [Support tables]

.scroll-snap-slide {
  scroll-snap-stop: always;
}
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JavaScript

If you do not want to add any additional behaviour, the JavaScript instance is not needed. This class dispatches several events and exposes a few methods, with which you can enhance your slider's behaviour.

Default behaviour:

import { ScrollSnapSlider } from 'scroll-snap-slider'

const element = document.querySelector('.example-slider')
const slider = new ScrollSnapSlider({ element })

slider.addEventListener('slide-start', function (event) {
  console.info(`Started sliding towards slide ${event.detail}.`)
})

slider.addEventListener('slide-pass', function (event) {
  console.info(`Passing slide ${event.detail}.`)
})

slider.addEventListener('slide-stop', function (event) {
  console.info(`Stopped sliding at slide ${event.detail}.`)
})
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Advanced config:

import { ScrollSnapSlider } from 'scroll-snap-slider'

// Do not automatically attach scroll listener
const slider = new ScrollSnapSlider({
  element: document.querySelector('.example-slider'),
  scrollTimeout: 50, // Sets a shorter timeout to detect scroll end
  roundingMethod: Math.round, // Dispatch 'slide-pass' events around the center of each slide
  // roundingMethod: Math.ceil, // Dispatch 'slide-pass' events as soon as the next one is visible
  // roundingMethod: Math.floor, // Dispatch 'slide-pass' events only when the next one is fully visible
  sizingMethod (slider) {

    // with padding
    return slider.element.firstElementChild.offsetWidth

    // without padding
    // return slider.element.firstElementChild.clientWidth
  }
})
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Plugins:

You can add one or multiple of the available Plugins:

• ScrollSnapAutoplay: Automatically slides at a given interval
• ScrollSnapLoop: Sliding past the last element shows the first without sliding to the start (and vice-versa)
• ScrollSnapDraggable: Drag the slider with your mouse. Note: this does not affect mobile behaviour and is not necessary for touch sliding.

import { ScrollSnapSlider, ScrollSnapAutoplay, ScrollSnapLoop } from 'scroll-snap-slider';

const element = document.querySelector('.example-slider')
const slider = new ScrollSnapSlider({ element }).with([
  new ScrollSnapAutoplay(1200),
  new ScrollSnapLoop
])
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Creating your own plugin:

export class CustomPlugin extends ScrollSnapPlugin {

  /**
   * Pass any config here
   * @param {*} config
   */
  constructor (config) {
    super()

    this.config = config
  }

  /**
   * Chose a unique plugin name. If you need multiple instances of the same plugin on a slider, each must return a unique id.
   * @return {String}
   */
  get id () {
    return 'lubba-wubba-dub-dub'
  }

  /**
   * Attach listeners, fetch DOM things, save reference to the slider
   * @param {ScrollSnapSlider} slider
   * @override
   */
  enable (slider) {
    // TODO method stub
  }

  /**
   * Free resources, remove listeners, ...
   * @override
   */
  disable () {
    // TODO method stub
  }
}
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API

Method	Description
slideTo(index: Number): void	Scrolls to slide at index.
addEventListener(...)	This is a shortcut for slider.element.addEventListener(...).
removeEventListener(...)	This is a shortcut for slider.element.removeEventListener(...).
attachEventListeners()	Enables the JS behaviour of this plugin. This is called in the constructor.
detachEventListeners()	Disables the JS behaviour of this plugin.
destroy()	Free resources and listeners. You can/should do slider = null after this.

Events

Events dispatched on the slider's element:

Event Name	Event Detail Type	Description
slide-start	Number	Dispatched when sliding starts toward slide at event.detail.
slide-pass	Number	Dispatched when sliding passes (crosses the threshold to) slide at event.detail. The threshold is defined/altered by the roundingMethod.
slide-stop	Number	Dispatched when sliding stopped at index event.detail, i.e. the last scroll event happened before scrollTimeout ms.

You can use the proxy methods addEventListener and removeEventListener to listen to them.

Public Properties

Property	Description
slide: Number (read only)	Currently active slide.
element: Element (read only)	The element passed into the constructor.
scrollTimeout: Number	Timeout delay in milliseconds used to catch the end of scroll events.
plugins: Map<String, ScrollSnapPlugin>	Map of plugins enabled for this slider

Support

Check out the support tables for CSS scroll snap. Note that it's up to you to inject or add vendor specific code.

Contributing

Feel free to open issues and pull requests, but keep the minimalist approach of this project in mind. When in doubt, open an issue first and we can discuss.

Running locally

yarn # install deps
yarn dev # run a local dev-server of the demo
yarn build # build the module 
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