Smooth Scroll Library

ScrollToSmooth

Support for older versions: If you need documentation for versions prior 3.0.0 visit this page

Lightweight Vanilla JS Smooth Scroll animation library without dependencies.

Create beautiful scroll animations with ease. ScrollToSmooth comes with a powerful set of options to get the best out of your project.
Powered by window.requestAnimationFrame() API and highly customizable.

Notice: If you just need simple smooth scrolling for a tags you might not need this library. Check out the native CSS scroll behavior and CSS scroll margin top.

View the Demo on CodePen 🎉

Getting Started | Usage | API | Noteworthy features | Browser Compatibility

Getting started

Installation

NPM

npm install scrolltosmooth

From a CDN

<!-- Latest version with all easings -->
<script src="https://cdn.jsdelivr.net/npm/scrolltosmooth/dist/scrolltosmooth.pkgd.min.js"></script>
<!-- Latest version with linear easing only -->
<script src="https://cdn.jsdelivr.net/npm/scrolltosmooth/dist/scrolltosmooth.min.js"></script>

Download

Directly download the repository and include the production ready code from the dist folder in your project.

Include the script in your code:

<script src="path/to/scrolltosmooth.min.js"></script>

Usage

import { 
  scrollToSmooth, 
  easeOutCubic 
} from 'scrolltosmooth';

let smoothScroll = new scrollToSmooth('a', {
  targetAttribute: 'href',
  duration: 400,
  durationRelative: false,
  durationMin: false,
  durationMax: false,
  easing: easeOutCubic,
  onScrollStart: (data) => {
    // do something
  },
  onScrollUpdate: (data) => {
    // do something
  },
  onScrollEnd: (data) => {
    // do something
  },
  offset: null
});
smoothScroll.init();

API

Smooth scroll Options

container

Type: string|element
Default: document

Specify a container element that contains the targets of the current initialization.

targetAttribute

Type: string
Default: 'href'

The attribute to determine the target element. Must be a valid selector!
You may use other attributes than href like for example data-scrollto so that the browsers default behaviour for anchor links does not change.

<span data-scrollto="#target">Scroll to Section 1<span>
<section id="target">
  Target Section
</section>

offset

Type: string|element|number
Default: null

Specify an element or a number to calculate the final position of the scrolling animation with offset to top.
Example: '#fixed-header'

Notice: You can also pass a numeric value for the offset option.

topOnEmptyHash

Type: boolean
default: true

If your targetAttribute contains an empty hash (#) on a href attribute force scroll to top.

duration

Type: number
Default: 400

Scroll animation duration in milliseconds.

durationRelative

Type: boolean|number
Default: false

durationRelative can be used to adjust the scroll animation duration by the amount of pixels to scroll.
If true scrollToSmooth will use the value of duration to calculate the amount of time in milliseconds to scroll the page by 1000px.
You can also use a number, for example 2000 to calculate the duration by 2000px.

Scroll distances that are below that number will take less time than defined in duration, while distances above will take longer to animate.

durationMin

Type: number
Default: null

durationMin represents the minimum amount of milliseconds to perform the animation when using a relative duration.

durationMax

Type: number
Default: null

just like durationMin, durationMax represents the maximum amount of milliseconds to perform the animation when using a relative duration.

easing

Type: string|function
Default: null

ScrollToSmooth comes with 31 predefined easing patterns.
By default scrollToSmooth is bundled with the linear easing type.

Linear easings output progress value is equal to the input progress value

• linear

Ease-In progress value gradually increases in speed

• easeInQuad
• easeInCubic
• easeInQuart
• easeInQuint
• easeInSine
• easeInExpo
• easeInCirc
• easeInElastic
• easeInBack
• easeInBounce

Ease-Out progress value gradually decreases in speed

• easeOutQuad
• easeOutCubic
• easeOutQuart
• easeOutQuint
• easeOutSine
• easeOutExpo
• easeOutCirc
• easeOutElastic
• easeOutBack
• easeOutBounce

Ease-In-Out progress value increases in speed and slows down back afterwards

• easeInOutQuad
• easeInOutCubic
• easeInOutQuart
• easeInOutQuint
• easeInOutSine
• easeInOutExpo
• easeInOutCirc
• easeInOutElastic
• easeInOutBack
• easeInOutBounce

How can I import individual easings?

Every easing bundled with ScrollToSmooth can be imported individually by

import { easingName } from 'scrolltosmooth';
new scrollToSmooth('a', {
  ...
  easing: easingName,
  ...
});

Can I use easing functions from another library?

You can import other easing functions and use it with ScrollToSmooth.
The only requirement is that the method must take only one parameter representing the absolute progress of the animation in the bounds of 0 (beginning of the animation) and 1 (end of animation).

Example:

import { cubic } from 'js-easing-library';
new scrollToSmooth('a', {
  ...
  easing: cubic,
  ...
});

You can also write your own easing functions:

Example:

new scrollToSmooth('a', {
  ...
  easing: (t) => t * t, // easeInQuad
  ...
});

onScrollStart

Type: function
Default: null

Callback function to be executed when the scrolling animation has started.

onScrollUpdate

Type: function
Default: null

Callback function to be executed while the scrolling animation runs.

onScrollEnd

Type: function
Default: null

Callback function to be executed when the scrolling animation has finished.

Methods

After creating a new instance of scrollToSmooth

let smoothScroll = new scrollToSmooth(document.querySelector('.scrollToSmooth-link'));

You can use the following public methods to interact with it:

init:

Initialize

smoothScroll.init();

scrollTo:

You can use the scrollTo method to animate the scrolling to a specific element on the page:

smoothScroll.scrollTo('.your-selector');
// OR
smoothScroll.scrollTo(document.querySelector('.your-selector'));

scrollTo can be also used with a numeric value.

Example:

smoothScroll.scrollTo(50);

scrollBy

scrollBy can be used just like scrollTo to trigger a scroll animation.
The only difference is you don't need a target element. Instead you can scroll by a fixed amount of pixels that gets added to the current scrollY.

smoothScroll.scrollBy(150);

cancelScroll:

while the animation is running you can call cancelScroll whenever you want to stop it immediately

smoothScroll.cancelScroll();

update:

Update the settings after initialization.

smoothScroll.update({
  duration: 1000,
  fixedHeader: '#my-header-element'
});

destroy:

Destroy the current instance of scrollToSmooth. You can then reinitialize the instance with the init method.

smoothScroll.destroy();

Callbacks

onScrollStart:

new scrollToSmooth('a', {
  ...
  onScrollStart: (data) => {  },
  ...
});

data contains an object with values for startPosition and endPosition

onScrollUpdate:

new scrollToSmooth('a', {
  ...
  onScrollUpdate: (data) => {  },
  ...
});

data contains an object with values for startPosition, currentPosition and endPosition

onScrollEnd:

new scrollToSmooth('a', {
  ...
  onScrollEnd: (data) => {  },
  ...
});

data contains an object with values for startPosition and endPosition

Custom Events

TODO: custom events section

Noteworthy features

Animating from the very top or bottom with special easings

ScrollToSmooth adds custom elements to the top and bottom of the page. These elements will simulate expanded boundaries of your document while the scroll animation is running. That means the animation wont stop on the bottom of your page when the easing function would normally exceed the documents height.

Working with fixed Headers

If your page has a fixed header scrollToSmooth can use this element and add an offset before each section.
This ensures that the final scroll position does not cover any elements that should normally be visible.

Usage:

<div id="fixed-header">
  <img src="path/to/your/logo.svg" />
</div>

new scrollToSmooth('a', {
  ...
  offset: '#fixed-header',
  // or
  offset: document.getElementById('fixed-header'),
  ...
});

Custom scroll triggers

You don't need real links to animate scrolling using ScrollToSmooth.
For example, if you want to use span tags as animation triggers you could do it like:

<nav>
  <span data-scrollto="#section-1">Scroll to section 1</span>
  <span data-scrollto="#section-2">Scroll to section 2</span>
</nav>
<section id="section-1"></section>
<section id="section-2"></section>

new scrollToSmooth('[data-scrollto]');

You can also define custom scroll triggers for specific events.
For example if you want to scroll down the page for 100px when clicking the spacebar:

const scrolltosmooth = new scrollToSmooth('a');

document.addEventListener('keyup', event => {
  if (event.keyCode === 32) {
    scrolltosmooth.scrollBy(100);
  }
})

Accessibility (a11y)

ScrollToSmooth automatically handles focus management after scrolling to an element so that the normal keyboard navigation won't get interrupted.

Browser Compatibility

| | | | | --- | --- | --- | --- | --- | --- | 15+ ✔ | 7+ ✔ | 10+ ✔ | 12+ ✔ | 15+ ✔ | 6+ ✔ |

Polyfills

Support for older browsers requires a polyfill for requestAnimationFrame()

Support me

If this project is helpfull you might support me out with a cup of coffee 🤗