overlayscrollbars
TypeScript icon, indicating that this package has built-in type declarations

2.9.2 • Public • Published

Downloads Version License Code Coverage Max. Bundle Size

Website   •   Examples

OverlayScrollbars

A javascript scrollbar plugin that hides the native scrollbars, provides custom styleable overlay scrollbars, and preserves the native functionality and feel.

Why?

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

Goals & Features

  • Simple, powerful and well-documented API
  • High browser compatibility - Firefox 59+, Chrome 55+, Opera 42+, Edge 15+ and Safari 10+
  • Fully Accessible - Native scrolling behavior is fully preserved
  • Can run on the server (Node, Deno and Bun) - SSR, SSG and ISR support
  • 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 required.
  • Leverage latest browser features - best performance in new browsers
  • Flow independent - supports all values for direction, flex-direction and writing-mode.
  • Supports scroll snapping
  • Supports all virtual scrolling libraries
  • Supports the `body' element
  • Easy and effective scrollbar styling
  • Highly customizable
  • TypeScript support - completely written in TypeScript
  • Dependency-free - 100% self-written to ensure small size and best functionality
  • High quality and fully typed framework versions for react, vue, angular, svelte and solid.

Choose your framework

In addition to the vanilla JavaScript version, you can use the official framework components & utilities:

React Vue Angular Svelte Solid

Getting started

npm & nodejs

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

npm install overlayscrollbars

Once installed, it can be imported:

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

Note: If the path 'overlayscrollbars/overlayscrollbars.css' is not working use 'overlayscrollbars/styles/overlayscrollbars.css' as the import path for the CSS file.

You can use this Node Example as an reference / starting point.

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.
  • Use the javascript files with the .es5 extension if you need to support older browsers, otherwise use the .es6 files.
  • For production use the javascript / stylesheet files with the .min extension.

Embed OverlayScrollbars manually in your HTML:

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

Use the global variable OverlayScrollbarsGlobal to access the api similar to how you can do it in nodejs / modules:

var { 
  OverlayScrollbars, 
  ScrollbarsHidingPlugin, 
  SizeObserverPlugin, 
  ClickScrollPlugin  
} = OverlayScrollbarsGlobal;

You can use this Browser Example as an reference / starting point.

The examples in this documentation will use the import syntax instead of the OverlayScrollbarsGlobal object. However, both versions are equivalent.

Initialization

The initialization of OverlayScrollbars is explicit per element. Only the scrollbars of the element on which the plugin is initialized will be changed. Scrollbars of child elements will remain unchanged unless the plugin is initialized on them as well.

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'), {});

Bridging initialization flickering

When you initialize OverlayScrollbars, it takes a few milliseconds to create and append all the elements to the DOM. During this time, the native scrollbars are still visible and will be switched out after the initialization is finished. This is seen as flickering.

To fix this behavior apply the data-overlayscrollbars-initialize attribute to the target element (and the html element if the target element is body).

<!-- for the body element -->
<html data-overlayscrollbars-initialize>
  <head></head>
  <body data-overlayscrollbars-initialize></body>
</html>

<!-- for all other elements -->
<div data-overlayscrollbars-initialize>
  OverlayScrollbars is applied to this div
</div>

Initialization with an Object

This is a in depth topic. Click here to read it.

The only required field is the target field. This is the field to which the plugin will be applied.
If you use the object initialization with only the target field, the result 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 handles generated elements. For example, you can specify an existing element as the `viewport' element. Then the library won't generate it, but use 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 create its own elements. These cases are very common when you want another library to work 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,
 },
}, {});

Last but not least, you can decide when to cancel the initialization:

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

In the above example, the initialization will be aborted if the native scrollbars are overlaid, or if your target is a body element and the plugin has determined that initializing to the body element would interfere with native functionality such as 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

This is a in depth topic. Click here to read it.

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,
    autoHideSuspend: false,
    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 visibility of a scrollbar if its scroll axis is able to have a scrollable overflow. (Scrollable overflow for an axis is only possible with the overflow behavior 'scroll' or 'visible-scroll').

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.autoHideSuspend

type default
boolean false

Suspend the autoHide functionality until the first scroll interaction was performed.
The default value for this option is false for backwards compatibility reasons but is recommended to be true for better accessibility.

scrollbars.dragScroll

type default
boolean true

Indicates whether you can drag the scrollbar handles for scrolling.

scrollbars.clickScroll

type default
boolean false

Note: This options requires the ClickScrollPlugin to work.

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.

TypeScript

// The options of a OverlayScrollbars instance.
type Options = {
  // Whether the padding shall be absolute.
  paddingAbsolute: boolean;
  // Whether to show the native scrollbars. Has only an effect it the native scrollbars are overlaid.
  showNativeOverlaidScrollbars: boolean;
  // Customizes the automatic update behavior.
  update: {
    /**
     * The given Event(s) from the elements with the given selector(s) will trigger an update.
     * Useful for everything the MutationObserver and ResizeObserver can't detect
     * e.g.: and Images `load` event or the `transitionend` / `animationend` events.
     */
    elementEvents: Array<[elementSelector: string, eventNames: string]> | null;
    /**
     * The debounce which is used to detect content changes.
     * If a tuple is provided you can customize the `timeout` and the `maxWait` in milliseconds.
     * If a single number customizes only the `timeout`.
     *
     * If the `timeout` is `0`, a debounce still exists. (its executed via `requestAnimationFrame`).
     */
    debounce: [timeout: number, maxWait: number] | number | null;
    /**
     * HTML attributes which will trigger an update if they're changed.
     * Basic attributes like `id`, `class`, `style` etc. are always observed and doesn't have to be added explicitly.
     */
    attributes: string[] | null;
    // A function which makes it possible to ignore a content mutation or null if nothing shall be ignored.
    ignoreMutation: ((mutation: MutationRecord) => any) | null;
  };
  // Customizes the overflow behavior per axis.
  overflow: {
    // The overflow behavior of the horizontal (x) axis.
    x: OverflowBehavior;
    // The overflow behavior of the vertical (y) axis.
    y: OverflowBehavior;
  };
  // Customizes appearance of the scrollbars.
  scrollbars: {
    // The scrollbars theme. The theme value will be added as `class` to all `scrollbar` elements of the instance.
    theme: string | null;
    // The scrollbars visibility behavior.
    visibility: ScrollbarsVisibilityBehavior;
    // The scrollbars auto hide behavior.
    autoHide: ScrollbarsAutoHideBehavior;
    // The scrollbars auto hide delay in milliseconds.
    autoHideDelay: number;
    // Whether the scrollbars auto hide behavior is suspended until a scroll happened.
    autoHideSuspend: boolean;
    // Whether its possible to drag the handle of a scrollbar to scroll the viewport.
    dragScroll: boolean;
    // Whether its possible to click the track of a scrollbar to scroll the viewport.
    clickScroll: boolean;
    // An array of pointer types which shall be supported.
    pointers: string[] | null;
  };
};

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

This is a in depth topic. Click here to read it.

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

initialized

arguments description
instance The instance which dispatched the event.

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

updated

arguments description
instance The instance which dispatched 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 dispatched.

Is dispatched after the instace was updated.

destroyed

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

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

scroll

arguments description
instance The instance which dispatched the event.
event The original event argument of the DOM event.

Is dispatched by scrolling the viewport.

TypeScript

// A mapping between event names and their listener arguments.
type EventListenerArgs = {
  // Dispatched after all elements are initialized and appended.
  initialized: [instance: OverlayScrollbars];
  // Dispatched after an update.
  updated: [instance: OverlayScrollbars, onUpdatedArgs: OnUpdatedEventListenerArgs];
  // Dispatched after all elements, observers and events are destroyed.
  destroyed: [instance: OverlayScrollbars, canceled: boolean];
  // Dispatched on scroll.
  scroll: [instance: OverlayScrollbars, event: Event];
};

interface OnUpdatedEventListenerArgs {
  // Hints which describe what changed in the DOM.
  updateHints: {
    // Whether the size of the host element changed.
    sizeChanged: boolean;
    // Whether the direction of the host element changed.
    directionChanged: boolean;
    // Whether the intrinsic height behavior changed.
    heightIntrinsicChanged: boolean;
    // Whether the overflow edge (clientWidth / clientHeight) of the viewport element changed.
    overflowEdgeChanged: boolean;
    // Whether the overflow amount changed.
    overflowAmountChanged: boolean;
    // Whether the overflow style changed.
    overflowStyleChanged: boolean;
    // Whether the scroll coordinates changed.
    scrollCoordinatesChanged: boolean;
    // Whether an host mutation took place.
    hostMutation: boolean;
    // Whether an content mutation took place.
    contentMutation: boolean;
  };
  // The changed options.
  changedOptions: PartialOptions;
  // Whether the update happened with an force invalidated cache.
  force: boolean;
}

Instance

The OverlayScrollbars instance is created by calling the OverlayScrollbars function with an element and options object.

const osInstance = OverlayScrollbars(document.body, {});

Instance Methods

This is a in depth topic. Click here to read it.

options(): Options

Get the current options of the instance.

returns description
Options The current options.

options(newOptions, pure?): Options

Sets the current options of the instance.

parameter type description
newOptions PartialOptions The new (partial) options which should be applied.
pure boolean / undefined Whether the options should be reset before the new options are added.
returns description
Options The complete new options.

on(eventListeners, pure?): Function

Adds event listeners to the instance.

parameter type description
eventListeners EventListeners An object which contains the added listeners. The fields are the event names and the values the listeners.
pure boolean / undefined Whether all already added event listeners should be removed before the new listeners are added.
returns description
Function A function which removes all added event listeners.

on(name, listener): Function

Adds a single event listener to the instance.

parameter type description
name string The event name.
listener Function The function which is invoked when the event is dispatched.
returns description
Function A function which removes the added event listener.

on(name, listeners): Function

Adds multiple event listeners to the instance.

parameter type description
name string The event name.
listeners Function[] The functions which are invoked when the event is dispatched.
returns description
Function A function which removes the added event listeners.

off(name, listener): void

Removes a single event listener from the instance.

parameter type description
name string The event name.
listener Function The function to be removed.

off(name, listeners): void

Removes multiple event listeners from the instance.

parameter type description
name string The event name.
listeners Function[] The functions to be removed.

update(force?): boolean

Updates the instance.

parameter type description
force boolean / undefined Whether the update should force the cache to be invalidated.
returns description
Function A boolean which indicates whether the update event was triggered through this update.

state(): State

Gets the instances state.

returns description
State An object which describes the state of the instance.

elements(): Elements

Gets the instances elments.

returns description
Elements An object which describes the elements of the instance.

destroy(): void

Destroys the instance and removes all added elements.

plugin(plugin: object): object | undefined

Gets the instance modules instance of the passed plugin.

returns description
object / undefined An object which describes the plugins instance modules instance or undefined if no instance was found.

TypeScript

// A simplified version of the OverlayScrollbars TypeScript interface.
interface OverlayScrollbars {
  // Get the current options of the instance.
  options(): Options;
  // Sets the current options of the instance.
  options(newOptions: PartialOptions, pure?: boolean): Options;

  // Adds event listeners to the instance.
  on(eventListeners: EventListeners, pure?: boolean): () => void;
  // Adds a single event listener to the instance.
  on<N extends keyof EventListenerArgs>(name: N, listener: EventListener<N>): () => void;
  // Adds multiple event listeners to the instance.
  on<N extends keyof EventListenerArgs>(name: N, listener: EventListener<N>[]): () => void;

  // Removes a single event listener from the instance.
  off<N extends keyof EventListenerArgs>(name: N, listener: EventListener<N>): void;
  // Removes multiple event listeners from the instance.
  off<N extends keyof EventListenerArgs>(name: N, listener: EventListener<N>[]): void;

  // Updates the instance.
  update(force?: boolean): boolean;

  // Gets the instances state.
  state(): State;

  // Gets the instances elements.
  elements(): Elements;

  // Destroys the instance and removes all added elements.
  destroy(): void;

  // Gets the instance modules instance of the passed plugin.
  plugin<P extends InstancePlugin>(osPlugin: P): InferInstancePluginModuleInstance<P> | undefined;
}

// Describes a OverlayScrollbars instances state.
interface State {
  // Describes the current padding in pixel.
  padding: TRBL;
  // Whether the current padding is absolute.
  paddingAbsolute: boolean;
  // The client width (x) & height (y) of the viewport in pixel.
  overflowEdge: XY<number>;
  // The overflow amount in pixel.
  overflowAmount: XY<number>;
  // The css overflow style of the viewport.
  overflowStyle: XY<OverflowStyle>;
  // Whether the viewport has an overflow.
  hasOverflow: XY<boolean>;
  // The scroll coordinates of the viewport.
  scrollCoordinates: {
    // The start (origin) scroll coordinates for each axis.
    start: XY<number>;
    // The end scroll coordinates for each axis.
    end: XY<number>;
  };
  // Whether the direction is considered rtl.
  directionRTL: boolean;
  // Whether the instance is considered destroyed.
  destroyed: boolean;
}

// Describes the elements of a OverlayScrollbars instance.
interface Elements {
  // The element the instance was applied to.
  target: HTMLElement;
  // The host element. Its the root of all other elements.
  host: HTMLElement;
  /**
   * The element which is responsible to apply correct paddings.
   * Depending on the Initialization it can be the same as the viewport element.
   */
  padding: HTMLElement;
  // The element which is responsible to do any scrolling.
  viewport: HTMLElement;
  /**
   * The element which is responsible to hold the content.
   * Depending on the Initialization it can be the same as the viewport element.
   */
  content: HTMLElement;
  /**
   * The element through which you can get the current `scrollLeft` or `scrollTop` offset.
   * Depending on the target element it can be the same as the viewport element.
   */
  scrollOffsetElement: HTMLElement;
  /**
   * The element through which you can add `scroll` events.
   * Depending on the target element it can be the same as the viewport element.
   */
  scrollEventElement: HTMLElement | Document;
  // The horizontal scrollbar elements.
  scrollbarHorizontal: CloneableScrollbarElements;
  // The vertical scrollbar elements.
  scrollbarVertical: CloneableScrollbarElements;
}

Static Object

The static OverlayScrollbars object.

OverlayScrollbars.plugin(SomePlugin);

Static Object Methods

This is a in depth topic. Click here to read it.

valid(osInstance): boolean

Checks whether the passed value is a valid and not destroyed overlayscrollbars instance

parameter type description
osInstance any The value to be checked.
returns description
boolean Whether the passed value is a valid and not destroyed overlayscrollbars instance.

env(): Environment

Gets the environment.

returns description
Environment An object which described the environment.

nonce(newNonce): void

Sets the nonce attribute for inline styles.

parameter type description
newNonce string / undefined The nonce attribute for inline styles.

plugin(plugin): object | undefined

Adds a single plugin.

parameter type description
plugin object The plugin to be added.
returns description
object / void An object which describes the plugins static modules instance or void if no instance was found.

plugin(plugins): (object | void)[]

Adds multiple plugins.

parameter type description
plugins object[] The plugins to be added.
returns description
(object / void)[] An array which describes the plugins static modules instances or undefined if no instance was found.

TypeScript

// The OverlayScrollbars static object.
interface OverlayScrollbarsStatic {
  // Gets the instance of the passed target or `undefined` the target has no instance.
  (target: InitializationTarget): OverlayScrollbars | undefined;
  // Initializes OverlayScrollbars to the passed target with passed options and event listeners.
  (target: InitializationTarget, options: PartialOptions, eventListeners?: EventListeners): OverlayScrollbars;

  // Checks whether the passed value is a valid and not destroyed overlayscrollbars instance.
  valid(osInstance: any): osInstance is OverlayScrollbars;

  // Gets the environment.
  env(): Environment;

  // Sets the nonce attribute for inline styles.
  nonce(newNonce: string | undefined): void;

  // Adds a single plugin.
  plugin(plugin: Plugin): InferStaticPluginModuleInstance<Plugin>
  // Adds multiple plugins.
  plugin(plugins: Plugin[]): InferStaticPluginModuleInstance<Plugin>[];
}

// Describes the OverlayScrollbars environment.
interface Environment {
  // The native scrollbars size of the browser / system.
  scrollbarsSize: XY<number>;
  // Whether the native scrollbars are overlaid.
  scrollbarsOverlaid: XY<boolean>;
  // Whether the browser supports native scrollbars hiding.
  scrollbarsHiding: boolean;
  // Whether the browser supports the ScrollTimeline API.
  scrollTimeline: boolean;
  // The default Initialization to use if nothing else is specified.
  staticDefaultInitialization: Initialization;
  // The default Options to use if nothing else is specified.
  staticDefaultOptions: Options;

  // Returns the current default Initialization.
  getDefaultInitialization(): Initialization;
  // Returns the current default Options.
  getDefaultOptions(): Options;

  /**
   * Sets a new default Initialization.
   * If the new default Initialization is partially filled, its deeply merged with the current default Initialization.
   * @param newDefaultInitialization The new default Initialization.
   * @returns The current default Initialization.
   */
  setDefaultInitialization(newDefaultInitialization: PartialInitialization): Initialization;
  /**
   * Sets new default Options.
   * If the new default Options are partially filled, they're deeply merged with the current default Options.
   * @param newDefaultOptions The new default Options.
   * @returns The current default options.
   */
  setDefaultOptions(newDefaultOptions: PartialOptions): Options;
}

Styling

OverlayScrollbars comes with two themes called os-theme-dark and os-theme-light. You can use the scrollbars.theme option to change the theme.

Custom themes can be done in several ways. The easiest and fastest way is to use the predefined set of CSS Custom Properties aka CSS variables. If that's not enough, you can add custom class names or add custom styling to the existing class names.

Styling in depth

This is a in depth topic. Click here to read it.

CSS Custom properties

OverlayScrollbars provides a set of CSS Custom Properties which makes scrollbar styling easy and fast:

.os-scrollbar {
  // The size of the scrollbar
  --os-size: 0;
  // The axis-perpedicular padding of the scrollbar (horizontal: padding-y, vertical: padding-x)
  --os-padding-perpendicular: 0;
  // The axis padding of the scrollbar (horizontal: padding-x, vertical: padding-y)
  --os-padding-axis: 0;
  // The border radius of the scrollbar track
  --os-track-border-radius: 0;
  // The background of the scrollbar track
  --os-track-bg: none;
  // The :hover background of the scrollbar track
  --os-track-bg-hover: none;
  // The :active background of the scrollbar track
  --os-track-bg-active: none;
  // The border of the scrollbar track
  --os-track-border: none;
  // The :hover background of the scrollbar track
  --os-track-border-hover: none;
  // The :active background of the scrollbar track
  --os-track-border-active: none;
  // The border radius of the scrollbar handle
  --os-handle-border-radius: 0;
  // The background of the scrollbar handle
  --os-handle-bg: none;
  // The :hover background of the scrollbar handle
  --os-handle-bg-hover: none;
  // The :active background of the scrollbar handle
  --os-handle-bg-active: none;
  // The border of the scrollbar handle
  --os-handle-border: none;
  // The :hover border of the scrollbar handle
  --os-handle-border-hover: none;
  // The :active border of the scrollbar handle
  --os-handle-border-active: none;
  // The min size of the scrollbar handle
  --os-handle-min-size: 33px;
  // The max size of the scrollbar handle
  --os-handle-max-size: none;
  // The axis-perpedicular size of the scrollbar handle (horizontal: height, vertical: width)
  --os-handle-perpendicular-size: 100%;
  // The :hover axis-perpedicular size of the scrollbar handle (horizontal: height, vertical: width)
  --os-handle-perpendicular-size-hover: 100%;
  // The :active axis-perpedicular size of the scrollbar handle (horizontal: height, vertical: width)
  --os-handle-perpendicular-size-active: 100%;
  // Increases the interactive area of the scrollbar handle.
  --os-handle-interactive-area-offset: 0;
}

You can change the properties for both scrollbars at once, or for each scrollbar axis. In the example below, I've chosen os-theme-custom as the theme name:

// horizontal and vertical scrollbar are 10px 
.os-theme-custom {
  --os-size: 10px;
}

// horizontal scrollbar is 10px
.os-theme-custom.os-scrollbar-horizontal {
  --os-size: 10px;
}
// vertical scrollbar is 20px
.os-theme-custom.os-scrollbar-vertical {
  --os-size: 20px;
}

You can then use your theme by assigning it via the scrollbars.theme option:

OverlayScrollbars(document.body, {
  scrollbars: {
    theme: 'os-theme-custom'
  }
});

Since scrollbar styles are usually simple, this set of options should be enough to get the styling you want. If you need more freedom, you can create your own styles by adding styling to the base class names described in the next section.

Scrollbars structure and CSS class names

The scrollbars HTML markup looks like:

<div class="os-scrollbar os-scrollbar-horizontal">
    <div class="os-scrollbar-track">
        <div class="os-scrollbar-handle">
        </div>
    </div>
</div>
<div class="os-scrollbar os-scrollbar-vertical">
    <div class="os-scrollbar-track">
        <div class="os-scrollbar-handle">
        </div>
    </div>
</div>

The class names are simplified, in a real application the .os-scrollbar element can have additional class names which modify the appearance (mostly visibility and alignment).

Below is a list of the most important class names you will encounter:

CSS class name description
.os-scrollbar The root element of a scrollbar.
.os-scrollbar-rtl Indicates a RTL direction of the host element the scrollbar belongs to.
.os-scrollbar-horizontal The root element of a horizontal scrollbar.
.os-scrollbar-vertical The root element of a vertical scrollbar.
.os-scrollbar-handle-interactive Indicates that the handle inside the scrollbar is interactive (scrollbars.dragScroll is true).
.os-scrollbar-track-interactive Indicates that the track inside the scrollbar is interactive (scrollbars.clickScroll is true).
.os-scrollbar-track The track element. This is the track of the nested handle element. If scrollbars.clickScroll is true this is the element users can click to change the scroll offset.
.os-scrollbar-handle The handle element. If scrollbars.dragScroll is true this is the handle users can drag to change the scroll offset.

If you create your own theme, please only use the classes listed above. All other classes are modifier classes used to change visibility, alignment and pointer-events of the scrollbars.

Gotchas

It is important that the chosen theme class name in your CSS file matches the assigned theme name in the options. If the CSS class name is .my-theme, the scrollbars.theme must be 'my-theme'.

Please be aware of your stack. For example, css-modules will change your class names to avoid naming collisions. Always check that your CSS is what you expect it to be.

Plugins

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

Consuming Plugins

Plugins are consumed like:

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

// single plugin
OverlayScrollbars.plugin(ScrollbarsHidingPlugin);

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

Plugins in depth

This is a in depth topic. Click here to read it.

Plugins are plain objects with a single field, the name of the field is the name of the plugin. This name is the plugins identifier and must be unique across all plugin. In case multiple plugins have the same name, the last added plugin overwrites previously added plugins.

Plugin Modules

A Plugin module is the constructor of a plugin modules instance. There are two kinds of plugin modules: static and instance. A single plugin must have one or more modules. Plugin modules can return an instance, but doesnt have to.

Static Plugin Module

The static plugin module is invoked when the plugin is added with the OverlayScrollbars.plugin function.

Example plugin with a static module:

const staticPlugin = {
  // plugin has the name `examplePlugin`
  examplePlugin: {
    // static function describes a static module and returns the module instance or void / undefined if no instance is needed
    // the `osStatic` parameter is the global `OverlayScrollbars` object
    static: (osStatic) => {
      let count = 0;
      const staticPluginModuleInstance = {
        getCount: () => count,
        increment: () => { count++ },
      }
      return staticPluginModuleInstance;
    }
  }
}

When the plugin is added with the OverlayScrollbars.plugin function, the static module instance is returned:

const staticModuleInstance = OverlayScrollbars.plugin(staticPlugin); // plugins static module is invoked
staticModuleInstance.count; // 0
staticModuleInstance.increment();
staticModuleInstance.count; // 1

Instance Plugin Module

The instance plugin module is invoked when a new OverlayScrollbars instance is created but before the initialized event is dispatched.

Example plugin with a instance module:

const instancePlugin = {
  // plugin has the name `examplePlugin`
  examplePlugin: {
    // instance function describes a instance module and returns the module instance or void / undefined if no instance is needed
    // the `osInstance` parameter is the OverlayScrollbar instance the plugin is bound to
    // the `event` parameter is a function which adds events to the instance which can't be removed from outside the plugin
    // the `osStatic` parameter is the gobal OverlayScrollbar object
    instance: (osInstance, event, osStatic) => {
      let count = 0;

      const instancePluginModuleInstance = {
        getCount: () => count,
        increment: () => { count++ },
      }

      // event which fires when the instance was initialized
      event('initialized', () => {
        console.log("instance initialized");
      });

      // event which fires when the viewport was scrolled
      const removeScrollEvent = event('scroll', () => {
        console.log("viewport scrolled");
        removeScrollEvent(); // removes the event after the first scroll
      });
      
      return instancePluginModuleInstance;
    }
  }
}

When the plugin is added with the OverlayScrollbars.plugin function, all OverlayScrollbar instances will automatically add the plugin from that point on. Previously created instances will not have the plugin. The instance module instance is returned with the osInstance.plugin function:

OverlayScrollbars.plugin(instancePlugin); // plugin is added

const osInstance = OverlayScrollbars(document.body, {}); // plugins instance module is invoked
const instancePluginInstance = osInstance.plugin(instancePlugin);

instancePluginInstance.count; // 0
instancePluginInstance.increment();
instancePluginInstance.count; // 1

TypeScript

// Describes a OverlayScrollbar plugin.
type Plugin<
  // the name of the plugin
  Name extends string = string,
  // the module instance type of the static module
  S extends PluginModuleInstance | void = PluginModuleInstance | void, 
  // the module instance type of the instance module
  I extends PluginModuleInstance | void = PluginModuleInstance | void 
> = {
  [pluginName in Name]: PluginModule<S, I>;
};

// Describes a OverlayScrollbar plugin which has only a static module.
type StaticPlugin<
  Name extends string = string,
  T extends PluginModuleInstance = PluginModuleInstance
> = Plugin<Name, T, void>;

// Describes a OverlayScrollbar plugin which has only a instance module.
type InstancePlugin<
  Name extends string = string,
  T extends PluginModuleInstance = PluginModuleInstance
> = Plugin<Name, void, T>;

// Infers the type of the static modules instance of the passed plugin.
type InferStaticPluginModuleInstance<T extends StaticPlugin>;

// Infers the type of the instance modules instance of the passed plugin.
type InferInstancePluginModuleInstance<T extends InstancePlugin>;

FAQ

How do I get / set the scroll position of an element I applied OverlayScrollbars to?

If you applied OverlayScrollbars to the body element you can use window.scrollX, window.scrollY, window.scroll, window.scrollTo, window.scrollBy or any other native api.

If the plugin was applied to any other element you have to get the viewport element with the instance.elements() function first. With this element you can use element.scrollTop, element.scrollLeft, element.scroll, element.scrollTo, element.scrollBy or any other native api.

const { viewport } = osInstance.elements();
const { scrollLeft, scrollTop } = viewport; // get scroll offset
viewport.scrollTo({ top: 0 }); // set scroll offset
Is it possible to limit / adjust the scrollbar handle length?

You can adjust a scrollbars handle length by setting a min-width / min-height and max-width / max-height style:

/* horizontal boundaries */
.os-scrollbar-horizontal .os-scrollbar-handle {
  min-width: 50px;
  max-width: 200px;
}
/* vertical boundaries */
.os-scrollbar-vertical .os-scrollbar-handle {
  min-height: 40px;
  max-height: 40px;
}

You can assign the same value to both properties to force the scrollbar to be always the same size.
Setting the width and height properties won't work since those are set by the plugin automatically.

Feature comparison to v1

  • The scroll function is missing. Planned as a plugin. (WIP)
  • Initialization to the textarea element isn't supported yet. Planned as a plugin. (WIP)

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)

Used by

Sponsors

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

License

MIT

Package Sidebar

Install

npm i overlayscrollbars

Weekly Downloads

495,048

Version

2.9.2

License

MIT

Unpacked Size

2.76 MB

Total Files

22

Last publish

Collaborators

  • kingsora