body-scroll-lock: A JavaScript repository from unabst

Why BSL?

Enables body scroll locking (for iOS Mobile and Tablet, Android, desktop Safari/Chrome/Firefox) without breaking scrolling of a target element (eg. modal/lightbox/flyouts/nav-menus).

Features:

disables body scroll WITHOUT disabling scroll of a target element
works on iOS mobile/tablet (!!)
works on Android
works on Safari desktop
works on Chrome/Firefox
works with vanilla JS and frameworks such as React / Angular / VueJS
supports nested target elements (eg. a modal that appears on top of a flyout)
can reserve scrollbar width
-webkit-overflow-scrolling: touch still works

Aren't the alternative approaches sufficient?

the approach document.body.ontouchmove = (e) => { e.preventDefault; return false; }; locks the body scroll, but ALSO locks the scroll of a target element (eg. modal).
the approach overflow: hidden on the body or html elements doesn't work for all browsers
the position: fixed approach causes the body scroll to reset
some approaches break inertia/momentum/rubber-band scrolling on iOS

Package Size:

LIGHT - package is only 2.2KB and 976B when gzipped (see here)!

Install

$ yarn add body-scroll-lock

or

$ npm install body-scroll-lock

You can now also load via a <script src='lib/bodyScrollLock.js /> tag (refer to the lib folder).

Usage examples

Common JS

// 1. Import the functions
const bodyScrollLock = require('body-scroll-lock');
const disableBodyScroll = bodyScrollLock.disableBodyScroll;
const enableBodyScroll = bodyScrollLock.enableBodyScroll;
  
// 2. Get a target element that you want to persist scrolling for (such as a modal/lightbox/flyout/nav). 
const targetElement = document.querySelector("#someElementId");
  
  
// 3. ...in some event handler after showing the target element...disable body scroll
disableBodyScroll(targetElement);
 
 
// 4. ...in some event handler after hiding the target element...
enableBodyScroll(targetElement);

React/ES6

// 1. Import the functions
import { disableBodyScroll, enableBodyScroll, clearAllBodyScrollLocks } from 'body-scroll-lock';
  
class SomeComponent extends React.Component {
  targetElement = null;
  
  componentDidMount() {
    // 2. Get a target element that you want to persist scrolling for (such as a modal/lightbox/flyout/nav). 
    this.targetElement = document.querySelector('#targetElementId');
  }
  
  showTargetElement = () => {
    // ... some logic to show target element
    
    // 3. Disable body scroll
    disableBodyScroll(this.targetElement);
  };
  
  hideTargetElement = () => {
    // ... some logic to hide target element
    
    // 4. Re-enable body scroll
    enableBodyScroll(this.targetElement);
  }
  
  componentWillUnmount() {
    // 5. Useful if we have called disableBodyScroll for multiple target elements,
    // and we just want a kill-switch to undo all that.
    // OR useful for if the `hideTargetElement()` function got circumvented eg. visitor 
    // clicks a link which takes him/her to a different page within the app.
    clearAllBodyScrollLocks();
  }

  render() {   
    return (
      <div>
        some JSX to go here
      </div> 
    );
  }
}

Vanilla JS

In the html:

<head>
  <script src="some-path-where-you-dump-the-javascript-libraries/lib/bodyScrollLock.js" />
</head>

Then in the javascript:

// 1. Get a target element that you want to persist scrolling for (such as a modal/lightbox/flyout/nav). 
const targetElement = document.querySelector("#someElementId");

// 2. ...in some event handler after showing the target element...disable body scroll
bodyScrollLock.disableBodyScroll(targetElement);

// 3. ...in some event handler after hiding the target element...
bodyScrollLock.enableBodyScroll(targetElement);

// 4. Useful if we have called disableBodyScroll for multiple target elements,
// and we just want a kill-switch to undo all that.
bodyScrollLock.clearAllBodyScrollLocks();

Demo

Check out the demo, powered by Now, @ https://bodyscrolllock.now.sh

Caveat

On iOS mobile (as is visible in the above demo), if you scroll the body directly even when the scrolling is locked (on iOS), the body scrolls - this is not what this package solves. It solves the typical case where a modal overlays the screen, and scrolling within the modal never causes the body to scroll too (when the top or bottom within the modal has been reached).

Since the latest update (thanks @Neddz), this caveat is no longer valid. iOS mobile behaviour should be the same as other devices (eg. Android Chrome).

Functions

Function	Arguments	Return	Description
`disableBodyScroll`	`targetElement: HTMLElement`	`void`	Disables body scroll while enabling scroll on target element
`enableBodyScroll`	`targetElement: HTMLElement` `options: BodyScrollOptions`	`void`	Enables body scroll and removing listeners on target element
`clearAllBodyScrollLocks`	`null`	`void`	Clears all scroll locks

Options

reserveScrollBarGap

optional, default: false

If the overflow property of the body is set to hidden, the body widens by the width of the scrollbar. This produces an unpleasant flickering effect, especially on websites with centered content. If the reserveScrollBarGap option is set, this gap is filled by a padding-right on the body element. If disableBodyScroll is called for the last target element, or clearAllBodyScrollLocks is called, the padding-right is automatically reset to the previous value.

import { enableBodyScroll } from 'body-scroll-lock';
import type { BodyScrollOptions } from 'body-scroll-lock';

const options: BodyScrollOptions = {
    reserveScrollBarGap: true
}

enableBodyScroll(targetElement, options);

References

https://medium.com/jsdownunder/locking-body-scroll-for-all-devices-22def9615177 https://stackoverflow.com/questions/41594997/ios-10-safari-prevent-scrolling-behind-a-fixed-overlay-and-maintain-scroll-posi

unabst/body-scroll-lock