Revelio

A very small library to reveal elements on scroll using an IntersectionObserver and CSS.

Installation

Install from npm using your favourite package manager.

yarn add revelio

Import into your project.

import { revelio } from 'revelio'

Usage

• Add a [data-revelio] attribute to DOM elements you wish to animate. This attribute identifies elements to observe for entries into the viewport.

• Add one or more comma-separated animation names as the [data-revelio] attribute value to the element.

• Define the CSS for the animation names used. This will control the actual animation. Basic examples:

:root {
  --animate-distance: 20px;
  --animate-timing: 450ms;
  --animate-easing: ease-out;
}

[data-revelio] {
  transition: all var(--animate-timing) var(--animate-easing);
}

[data-revelio*="slide-up"] {
  transform: translateY(var(--animate-distance));
}

[data-revelio*="fade-in"] {
  opacity: 0;
}

• Call the revelio() method in your code.

• That's it! Ensure that the bundle containing the revelio script is loaded with the defer attribute or has a DOMContentLoaded event listener to ensure that all DOM elements are detected correctly.

Options

• Users can tailor revelio by including a revelioConfig object on the global window object. This must be included in the HTML before the bundle containing revelio.

// Default values shown.
<script>
  window.revelioConfig = {
    root: null,
    rootMargin: null,
    threshold: 0.25,
    ignoreDisplayNone: true,
    ignoreHidden: false,
  };
</script>

Variable	Description
root	IntersectionObserver root element. Default is the browser viewport, but can be any scrollable element represented by a DOMString (eg. document.body)
rootMargin	Used to modify the root element shape. Can only be set if root is not null (viewport).
threshold	Amount (%) that an element must have entered the root to trigger the animation. Decimal value from 0.00 to 1.00
ignoreDisplayNone	Whether to ignore elements with display: none when triggering animations. Boolean value that defaults to true.
ignoreHidden	Whether to ignore elements with visibility: hidden when triggering animations. Boolean value that defaults to false.