Rafscroll

Rafscroll is a small library (<3kb esm or <4kb umd) to smooth scroll windows and DOM elements by using a browser’s native requestAnimationFrame, ensuring optimal scrolling without impacting site performance. Rafscroll can operate on both the x and y axis with various easing functions.

Demo here

Get Started

Note: This readme assumes you are using a build tool like webpack

First install from NPM or yarn:

npm install @braid/rafscroll
- or -
yarn add @braid/rafscroll

Then import/require the library in your front end code:

// main.js

import rafscroll from '@braid/rafscroll'

Rafscroll exports a function. Calling this function creates a new instance of rafscroll.

let scroller = rafscroll(element, {...options})

The returned object can then have it's X or Y axis animated by calling scrollTop() or/and scrollLeft(). The return value of either of these is a Promise that resolves when the scroll animation is complete. For convenience rafscroll also uses some intelligent defaults — the window is the default element, and the the default easing is quadratic.

A full example:

import rafscroll from '@braid/rafscroll'

// Scroll 100px down the page after 1 second.
setTimeout(async () => {
    await rafscroll().scrollTop(100)
    alert('Finished scrolling')
}, 1000)

Options

Available options to pass as a second argument to rafscroll:

Option	Values	Default
duration	any Number in milliseconds	500
easing	'quadratic', 'linear', or a custom Function	'quadratic'

Custom easing functions receive an object containing 4 properties:

{current, duration, posDelta, posStart}

They should return a numeric value representing the current position. For example the linear easing function already included in rafscroll is:

function ({current, duration, posDelta, posStart}) {
    return (current / duration) * posDelta + posStart
}

Sponsor

Rafscroll is written and maintained by Braid LLC, and offered freely under an MIT license.