lenis by darkroomengineering - RepoMind Architecture & Analysis

Introduction

Lenis ("smooth" in latin) is a lightweight, robust, and performant smooth scroll library. It's designed by @darkroom.engineering to be simple to use and easy to integrate into your projects. It's built with performance in mind and is optimized for modern browsers. It's perfect for creating smooth scrolling experiences on your website such as WebGL scroll syncing, parallax effects, and much more, see Demo and Showcase.

Read our Manifesto to learn more about the inspiration behind Lenis.

Sponsors
Packages
Showcase
Installation
Setup
Settings
Properties
Methods
Events
Considerations
Limitations
Troubleshooting
Tutorials
Plugins
License

Packages

Installation

Using a package manager:

npm i lenis
# or
yarn add lenis
# or
pnpm add lenis

import Lenis from 'lenis'

Using scripts:

<script src="https://unpkg.com/lenis@1.3.17/dist/lenis.min.js"></script>

Setup

Basic:

// Initialize Lenis
const lenis = new Lenis({
  autoRaf: true,
});

// Listen for the scroll event and log the event data
lenis.on('scroll', (e) => {
  console.log(e);
});

Custom raf loop:

// Initialize Lenis
const lenis = new Lenis();

// Use requestAnimationFrame to continuously update the scroll
function raf(time) {
  lenis.raf(time);
  requestAnimationFrame(raf);
}

requestAnimationFrame(raf);

Recommended CSS:

Import stylesheet:

import 'lenis/dist/lenis.css'

Or link the CSS file:

<link rel="stylesheet" href="https://unpkg.com/lenis@1.3.17/dist/lenis.css">

Or add it manually:

See lenis.css stylesheet

GSAP ScrollTrigger:

// Initialize a new Lenis instance for smooth scrolling
const lenis = new Lenis();

// Synchronize Lenis scrolling with GSAP's ScrollTrigger plugin
lenis.on('scroll', ScrollTrigger.update);

// Add Lenis's requestAnimationFrame (raf) method to GSAP's ticker
// This ensures Lenis's smooth scroll animation updates on each GSAP tick
gsap.ticker.add((time) => {
  lenis.raf(time * 1000); // Convert time from seconds to milliseconds
});

// Disable lag smoothing in GSAP to prevent any delay in scroll animations
gsap.ticker.lagSmoothing(0);

React:

See documentation for lenis/react.

Settings

Option	Type	Default	Description
`wrapper`	`HTMLElement, Window`	`window`	The element that will be used as the scroll container.
`content`	`HTMLElement`	`document.documentElement`	The element that contains the content that will be scrolled, usually `wrapper`'s direct child.
`eventsTarget`	`HTMLElement, Window`	`wrapper`	The element that will listen to `wheel` and `touch` events.
`smoothWheel`	`boolean`	`true`	Smooth the scroll initiated by `wheel` events.
`lerp`	`number`	`0.1`	Linear interpolation (lerp) intensity (between 0 and 1).
`duration`	`number`	`1.2`	The duration of scroll animation (in seconds). Useless if lerp defined.
`easing`	`function`	`(t) => Math.min(1, 1.001 - Math.pow(2, -10 * t))`	The easing function to use for the scroll animation, our default is custom but you can pick one from Easings.net. Useless if lerp defined.
`orientation`	`string`	`vertical`	The orientation of the scrolling. Can be `vertical` or `horizontal`.
`gestureOrientation`	`string`	`vertical`	The orientation of the gestures. Can be `vertical`, `horizontal` or `both`.
`syncTouch`	`boolean`	`false`	Mimic touch device scroll while allowing scroll sync (can be unstable on iOS<16).
`syncTouchLerp`	`number`	`0.075`	Lerp applied during `syncTouch` inertia.
`touchInertiaExponent`	`number`	`1.7`	Manage the strength of syncTouch inertia.
`wheelMultiplier`	`number`	`1`	The multiplier to use for mouse wheel events.
`touchMultiplier`	`number`	`1`	The multiplier to use for touch events.
`infinite`	`boolean`	`false`	Enable infinite scrolling! `syncTouch: true` is required on touch devices (See example).
`autoResize`	`boolean`	`true`	Resize instance automatically based on `ResizeObserver`. If `false` you must resize manually using `.resize()`.
`prevent`	`function`	`undefined`	Manually prevent scroll to be smoothed based on elements traversed by events. If `true` is returned, it will prevent the scroll to be smoothed. Example: `(node) => node.classList.contains('cookie-modal')`.
`virtualScroll`	`function`	`undefined`	Manually modify the events before they get consumed. If `false` is returned, the scroll will not be smoothed. Examples: `(e) => { e.deltaY /= 2 }` (to slow down vertical scroll) or `({ event }) => !event.shiftKey` (to prevent scroll to be smoothed if shift key is pressed).
`overscroll`	`boolean`	`true`	Similar to CSS overscroll-behavior (https://developer.mozilla.org/en-US/docs/Web/CSS/overscroll-behavior).
`autoRaf`	`boolean`	`false`	Whether or not to automatically run `requestAnimationFrame` loop.
`anchors`	`boolean, ScrollToOptions`	`false`	Scroll to anchor links when clicked. If `true` is passed, it will enable anchor links with default options. If `ScrollToOptions` is passed, it will enable anchor links with the given options.
`autoToggle`	`boolean`	`false`	Automatically start or stop the lenis instance based on the wrapper's overflow property, ⚠️ this requires Lenis recommended CSS. Safari > 17.3, Chrome > 116 and Firefox > 128 (https://caniuse.com/?search=transition-behavior).
`allowNestedScroll`	`boolean`	`false`	Allow nested scrolls. If `true` is passed, it will allow nested scrolls. If `false` is passed, it will not allow nested scrolls. ⚠️ To be used with caution since this can lead to performance issues, prefer using `prevent` or `data-lenis-prevent` instead.
`naiveDimensions`	`boolean`	`false`	If `true`, Lenis will use naive dimensions calculation. ⚠️ Be careful, this has a performance impact.
`stopInertiaOnNavigate`	`boolean`	`false`	If `true`, Lenis will stop inertia when an internal link is clicked.

Properties

Property	Type	Description
`animatedScroll`	`number`	Current scroll value
`dimensions`	`object`	Dimensions instance
`direction`	`number`	`1`: scrolling up, `-1`: scrolling down
`emitter`	`object`	Emitter instance
`options`	`object`	Instance options
`targetScroll`	`number`	Target scroll value
`time`	`number`	Time elapsed since instance creation
`actualScroll`	`number`	Current scroll value registered by the browser
`lastVelocity`	`number`	last scroll velocity
`velocity`	`number`	Current scroll velocity
`isHorizontal` (getter)	`boolean`	Whether or not the instance is horizontal
`isScrolling` (getter)	`boolean, string`	Whether or not the scroll is being animated, `smooth`, `native` or `false`
`isStopped` (getter)	`boolean`	Whether or not the user should be able to scroll
`limit` (getter)	`number`	Maximum scroll value
`progress` (getter)	`number`	Scroll progress from `0` to `1`
`rootElement` (getter)	`HTMLElement`	Element on which Lenis is instanced
`scroll` (getter)	`number`	Current scroll value (handles infinite scroll if activated)
`className` (getter)	`string`	`rootElement` className

Methods

Method	Description	Arguments
`raf(time)`	Must be called every frame for internal usage.	`time`: in ms
`scrollTo(target, options)`	Scroll to target.	`target`: goal to reach<ul><li>`number`: value to scroll in pixels</li><li>`string`: CSS selector or keyword (`top`, `left`, `start`, `bottom`, `right`, `end`)</li><li>`HTMLElement`: DOM element</li></ul>`options`<ul><li>`offset`(`number`): equivalent to `scroll-padding-top`</li><li>`lerp`(`number`): animation lerp intensity</li><li>`duration`(`number`): animation duration (in seconds)</li><li>`easing`(`function`): animation easing</li><li>`immediate`(`boolean`): ignore duration, easing and lerp</li><li>`lock`(`boolean`): whether or not to prevent the user from scrolling until the target is reached</li><li>`force`(`boolean`): reach target even if instance is stopped</li><li>`onComplete`(`function`): called when the target is reached</li><li>`userData`(`object`): this object will be forwarded through `scroll` events</li></ul>
`on(id, function)`	`id` can be any of the following instance events to listen.
`stop()`	Pauses the scroll
`start()`	Resumes the scroll
`resize()`	Compute internal sizes, it has to be used if `autoResize` option is `false`.
`destroy()`	Destroys the instance and removes all events.

Events

Event	Callback Arguments
`scroll`	Lenis instance
`virtual-scroll`	`{deltaX, deltaY, event}`

Considerations

Nested scroll

Using Javascript

<div id="modal">scrollable content</div>

const lenis = new Lenis({
  prevent: (node) => node.id === 'modal',
})

See example

Using HTML

<div data-lenis-prevent>scrollable content</div>

See example

Prevent wheel events only:

<div data-lenis-prevent-wheel>scrollable content</div>

Prevent touch events only:

<div data-lenis-prevent-touch>scrollable content</div>

Anchor links

By default, Lenis will prevent anchor links from working while scrolling. To enable them, you must set anchors: true.

new Lenis({
  anchors: true
})

You can also use scrollTo options:

new Lenis({
  anchors: {
    offset: 100,
    onComplete: ()=>{
      console.log('scrolled to anchor')
    }
  }
})

Limitations

no support for CSS scroll-snap, you must use (lenis/snap)
capped to 60fps on Safari (source) and 30fps on low power mode
smooth scroll will stop working over iframe since they don't forward wheel events
position fixed seems to lag on MacOS Safari pre-M1 (source)
touch events may behave unexpectedly when syncTouch is enabled on iOS < 16
nested scroll containers require proper configuration to work correctly

Troubleshooting

Make sure you use the latest version of Lenis
Include the recommended CSS
If using GSAP ScrollTrigger, ensure proper integration (see GSAP ScrollTrigger setup section)
Test without Lenis to ensure your element/page is scrollable
Be sure to use autoRaf: true or manually call lenis.raf(time) in your animation loop

Tutorials

Plugins

r3f-scroll-rig by 14islands
locomotive-scroll by Locomotive

darkroomengineering / lenis

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Repository Summary (README)