Performance focused, lightweight scroll animation library

Sal

Performance focused, lightweight (less than 2.8 kb) scroll animation library, written in vanilla JavaScript. No dependencies!

Sal (Scroll Animation Library) was created to provide a performant and lightweight solution for animating elements on scroll. It’s based on the Intersection Observer, which gives amazing performance in terms of checking the element’s presence in the viewport.

Note: Intersection Observer API is an experimental technology so be sure to consult the browser compatibility table and consider using a polyfill.

Table of Contents

• Install
• Usage
• Animations
• Options
• API
• Events
• License

Install

# Usage with NPM
$ npm install --save sal.js

# and with Yarn
$ yarn add sal.js

Load it with your favorite module loader or use as a global variable

// ES6 modules
import sal from 'sal.js'

// CommonJS modules
var sal = require('sal.js')

And remember to add styles

// Webpack
@import '~sal.js/sal.css';

// Other
@import './node_modules/sal.js/dist/sal.css';

Usage

In HTML, add a data-sal attribute with the animation name as value, e.g.:

<div data-sal="fade"></div>

Then simply initialize Sal in your script file:

sal();

It will look for all elements with a data-sal attribute and launch their animation when in viewport.

Animations

In sal.js you can easily change animation’s options, by adding a proper data attribute:

• data-sal-duration - changes duration of the animation (from 200 to 2000 ms)
• data-sal-delay - adds delay to the animation (from 5 to 1000 ms)
• data-sal-easing - sets easing for the animation (see easings.net for reference)

For example:

<div
  data-sal="slide-up"
  data-sal-delay="300"
  data-sal-easing="ease-out-back"
></div>

The library supports several animations:

• fade
• slide-up
• slide-down
• slide-left
• slide-right
• zoom-in
• zoom-out
• flip-up
• flip-down
• flip-left
• flip-right

Additionaly, when you want to customise animation’s properties - duration, delay and easing, you can use CSS variables to set any value you want. See the following example:

<div
  data-sal="slide-up"
  style="--sal-duration: 3s; --sal-delay: 2s;"
></div>

Supported custom properties:

• --sal-duration
• --sal-delay
• --sal-easing

Remember, that you can use only data attributes (e.g. data-sal-delay) or CSS custom properties (e.g. --sal-delay). Data attributes have precedence over CSS custom properties.

Options

You can set options during Sal’s initialization, e.g.:

sal({
  threshold: 1,
  once: false,
});

Advanced options

API

Public methods are available after Sal’s initialization:

const scrollAnimations = sal();

scrollAnimations.disable();

Changing options after intialization

If you want to change Sal’s options once it’s been initialized, you should use reset method, that allows you to pass new set of options. It can be useful, when you would like to provide different options for specific viewport sizes.

const scrollAnimations = sal();

// Provide new options
scrollAnimations.reset({
  selector: 'animated-element',
  once: true,
});

Events

This library supports events, fired when element is entering or exiting viewport (they are named sal:in and sal:out by default). Property detail is IntersectionObserverEntry object.

You can attach listener to specific element.

// Get element with ".animated" class, which has "data-sal" attribute
const element = document.querySelector('.animated');

element.addEventListener('sal:in', ({ detail }) => {
  console.log('entering', detail.target);
});

or to the whole document

document.addEventListener('sal:out', ({ detail }) => {
  console.log('exiting', detail.target);
});

Note: This library uses Custom Event to trigger events on animated elements. Check the compatibility table to know if your browser supports it and use a polyfill if needed.

License

Created by Mirek Ciastek. Released under the MIT License.