OverlayScrollbars is a javascript scrollbar plugin that hides native scrollbars, provides custom styleable overlay scrollbars and keeps the native functionality and feeling.

This is the documentation for version 2.x. which is currently in beta. You can read the version 1.x docs here or on the website.

Why

I've created this plugin because I hate ugly and space consuming scrollbars. Similar plugins haven't met my requirements in terms of features, quality, simplicity, license or browser support.

Goals & Features

• Simple, powerful and good documented API
• High browser compatibility - Firefox, Chrome, Opera, Edge, Safari 10+ and IE 11
• Tested on various devices - Mobile, Desktop and Tablet
• Tested with various (and mixed) inputs - Mouse, touch and pen
• Treeshaking - bundle only what you really need
• Automatic update detection - no polling
• Usage of latest browser features - best performance in new browsers
• Bidirectional - LTR or RTL direction support
• Simple and effective scrollbar styling
• TypeScript support - fully written in TypeScript

Getting started

npm & Node

OverlayScrollbars can be downloaded from npm or the package manager of your choice:

npm install overlayscrollbars

After installation it can be imported:

import 'overlayscrollbars/overlayscrollbars.css';
import { OverlayScrollbars } from 'overlayscrollbars';

Manual download & embedding

You can use OverlayScrollbars without any bundler or package manager.
Simply download it from the Releases or use a CDN.

• Use the javascript files with the .browser extension.
• If you target old browsers use the .es5 javascript file, for new browsers .es6.
• For production use the javascript / stylesheet files with the .min extension.

Embedd OverlayScrollbars manually in your HTML:

<link type="text/css" href="path/to/overlayscrollbars.css" rel="stylesheet" />
<script type="text/javascript" src="path/to/overlayscrollbars.js" defer></script>

Initialization

Note: During initialization its expected that the CSS file is loaded and parsed by the browser.

You can initialize either directly with an Element or with an Object where you have more control over the initialization process.

// simple initialization with an element
const osInstance = OverlayScrollbars(document.querySelector('#myElement'), {});

Initialization with an Object

Note: For now please refer to the TypeScript definitions for a more detailed description of all possibilities.

The only required field is the target field. This is the field to which the plugin is applied to.
If you use the object initialization only with the target field, the outcome is equivalent to the element initialization:

// Both initializations have the same outcome

OverlayScrollbars(document.querySelector('#myElement'), {});
OverlayScrollbars({ target: document.querySelector('#myElement') }, {});

In the initialization object you can specify how the library is handling generated elements. For example you can appoint an existing element as the viewport element. Like this the library won't generate it but take the specified element instead:

OverlayScrollbars({ 
 target: document.querySelector('#target'),
 elements: {
   viewport: document.querySelector('#viewport'),
 },
}, {});

This is very useful if you have a fixed DOM structure and don't want OverlayScrollbars to generate its own elements. Those cases arise very often when you want an other library to work together with OverlayScrollbars.

---

You can also decide to which element the scrollbars should be applied to:

OverlayScrollbars({ 
 target: document.querySelector('#target'),
 scrollbars: {
   slot: document.querySelector('#target').parentElement,
 },
}, {});

---

And last but not least you can decide when the initialization should be canceled:

OverlayScrollbars({ 
 target: document.querySelector('#target'),
 cancel: {
   nativeScrollbarsOverlaid: true,
   body: null,
 }
}, {});

In the above example the initialization is canceled when the native scrollbars are overlaid or when your target is a body element and the plugin determined that a initialization to the body element would affect native functionality like window.scrollTo.

Options

You can initialize OverlayScrollbars with an initial set of options, which can be changed at any time with the options method:

OverlayScrollbars(document.querySelector('#myElement'), {
  overflow: {
    x: 'hidden',
  },
});

Options in depth

The default options are:

const defaultOptions = {
  paddingAbsolute: false,
  showNativeOverlaidScrollbars: false,
  update: {
    elementEvents: [['img', 'load']],
    debounce: [0, 33],
    attributes: null,
    ignoreMutation: null,
  },
  overflow: {
    x: 'scroll',
    y: 'scroll',
  },
  scrollbars: {
    theme: 'os-theme-dark',
    visibility: 'auto',
    autoHide: 'never',
    autoHideDelay: 1300,
    dragScroll: true,
    clickScroll: false,
    pointers: ['mouse', 'touch', 'pen'],
  },
};

paddingAbsolute

type	default
boolean	false

Indicates whether the padding for the content shall be absolute.

showNativeOverlaidScrollbars

type	default
boolean	false

Indicates whether the native overlaid scrollbars shall be visible.

update.elementEvents

type	default
Array<[string, string]> | null	[['img', 'load']]

An array of tuples. The first value in the tuple is an selector and the second value are event names. The plugin will update itself if any of the elements with the specified selector will emit any specified event. The default value can be interpreted as "The plugin will update itself if any img element emits an load event."

update.debounce

type	default
[number, number] | number | null	[0, 33]

Note: If 0 is used for the timeout, requestAnimationFrame instead of setTimeout is used for the debounce.

Debounces the MutationObserver which tracks changes to the content. If a tuple is passed, the first value is the timeout and second is the max wait. If only a number is passed you specify only the timeout and there is no max wait. With null there is no debounce. Usefull to fine-tune performance.

update.attributes

type	default
string[] | null	null

Note: There is a base array of attributes that the MutationObserver always observes, even if this option is null.

An array of additional attributes that the MutationObserver should observe for the content.

update.ignoreMutation

type	default
((mutation) => any) | null	null

A function which receives a MutationRecord as an argument. If the function returns a truthy value the mutation will be ignored and the plugin won't update. Usefull to fine-tune performance.

overflow.x

type	default
string	'scroll'

Note: Valid values are: 'hidden', 'scroll', 'visible', 'visible-hidden' and 'visible-scroll'.

The overflow behavior for the horizontal (x) axis.

overflow.y

type	default
string	'scroll'

Note: Valid values are: 'hidden', 'scroll', 'visible', 'visible-hidden' and 'visible-scroll'.

The overflow behavior for the vertical (y) axis.

scrollbars.theme

type	default
string | null	'os-theme-dark'

Applies the specified theme (classname) to the scrollbars.

scrollbars.visibility

type	default
string	'auto'

Note: Valid values are: 'visible', 'hidden', and 'auto'.

The base visibility of the scrollbars.

scrollbars.autoHide

type	default
string	'never'

Note: Valid values are: 'never', 'scroll', 'leave' and 'move'.

The possibility to hide visible scrollbars automatically after a certain user action.

scrollbars.autoHideDelay

type	default
number	1300

The delay in milliseconds before the scrollbars are hidden automatically.

scrollbars.dragScroll

type	default
boolean	true

Indicates whether you can drag the scrollbar handles for scrolling.

scrollbars.clickScroll

type	default
boolean	false

Indicates whether you can click on the scrollbar track for scrolling.

scrollbars.pointers

type	default
string[] | null	['mouse', 'touch', 'pen']

The PointerTypes the plugin should react to.

Events

You can initialize OverlayScrollbars with an initial set of events, which can be managed at any time with the on and off methods:

OverlayScrollbars(document.querySelector('#myElement'), {}, {
  updated(osInstance, onUpdatedArgs) {
    // ...
  }
});

Events in depth

Note: Every event receives the instance from which it was fired as the first argument. Always.

initialized

arguments	description
instance	The instance which fired the event.

Is fired after all generated elements, observers and events were appended to the DOM.

updated

arguments	description
instance	The instance which fired the event.
onUpdatedArgs	An object which describes the update in detail.

Note: If an update was triggered but nothing changed, the event won't be fired.

Is fired after the instace was updated.

destroyed

arguments	description
instance	The instance which fired the event.
canceled	An boolean which indicates whether the initialization was canceled and thus destroyed.

Is fired after all generated elements, observers and events were removed from the DOM.

Instance Methods

Note: For now please refer to the TypeScript definitions for a more detailed description.

interface OverlayScrollbars {
  options(): Options;
  options(newOptions: DeepPartial<Options>): Options;

  update(force?: boolean): OverlayScrollbars;

  destroy(): void;

  state(): State;

  elements(): Elements;

  on<N extends keyof EventListenerMap>(name: N, listener: EventListener<N>): () => void;
  on<N extends keyof EventListenerMap>(name: N, listener: EventListener<N>[]): () => void;

  off<N extends keyof EventListenerMap>(name: N, listener: EventListener<N>): void;
  off<N extends keyof EventListenerMap>(name: N, listener: EventListener<N>[]): void;
}

Static Methods

Note: For now please refer to the TypeScript definitions for a more detailed description.

interface OverlayScrollbarsStatic {
  (target: InitializationTarget): OverlayScrollbars | undefined;
  (
    target: InitializationTarget,
    options: DeepPartial<Options>,
    eventListeners?: InitialEventListeners
  ): OverlayScrollbars;

  plugin(plugin: Plugin | Plugin[]): void;
  valid(osInstance: any): boolean;
  env(): Environment;
}

Plugins

Everything thats considered not core functionality or old browser compatibility is exposed via a plugin. This is done because all unused plugins are treeshaken and thus won't end up in your final bundle. OverlayScrollbars comes with the following plugins:

• ScrollbarsHidingPlugin: Is needed for old browsers which aren't supporting nativ scrollbar styling features. You can find the list of browsers where you need this plugin here (note that even though iOS Safari >= 14 is marked as unsupported you only need this plugin for iOS < 7.1).
• SizeObserverPlugin: Is needed for old browsers which aren't supporting the ResizeObserver api. You can find the list of browsers where you need this plugin here
• ClickScrollPlugin: If you want to use the option scrollbars: { clickScroll: true }.

Consuming Plugins

You can consume plugins like:

import { 
  OverlayScrollbars, 
  ScrollbarsHidingPlugin, 
  SizeObserverPlugin, 
  ClickScrollPlugin 
} from 'overlayscrollbars';

// single plugin
OverlayScrollbars.plugin(ScrollbarsHidingPlugin);

// multiple plugins
OverlayScrollbars.plugin([SizeObserverPlugin, ClickScrollPlugin]);

Writing Plugins

You can write and publish your own Plugins. This section is a work in progress.

Sponsors

Thanks to BrowserStack for sponsoring open source projects and letting me test OverlayScrollbars for free.

Future Plans

• Provide plugin based support for missing features. (treeshakeable)
• Frequent updates in terms of bug-fixes and enhancements. (always use latest browser features)
• Improve tests. (unit & browser tests)

License

MIT