An easily designable, cross browser (!!), custom scroll with ReactJS.

The actual scroll is still the native one - Meaning the scroll animations and scroll rate work as always The only thin that is different is the visible design and scrollbar layout.

npm i react-custom-scroll --save

• Same design on all browsers
• Scrollbar is above the content instead of floating to the side - same layout on scrolled content as not scrolled content

Custom scroll component is available in module or commonJS format.
It is located in /dist directory
From unpkg cdn:

• Js file

Wrap your content with the custom scroll component
Remove any overflow style properties from your content root component - The custom scroll will take care of it

import { CustomScroll } from "react-custom-scroll";

<CustomScroll>
  your content
</CustomScroll>

Your own custom design can be applied by styling these 2 classes in your css:

• rcs-custom-scrollbar - this class styles the container of the scroll handle, you can use it if your handle width is greater than the default.
• rcs-inner-handle - this class styles the handle itself, you can use it to change the color, background, border and such of the handle

You can see a usage example in the demo page.

• allowOuterScroll : boolean, default false. Blocks outer scroll while scrolling the content
• heightRelativeToParent : string, default undefined. Content height limit is relative to parent - the value should be the height limit.
• flex : number, default undefined. If present will apply to the content wrapped by the custom scroll.
  This prop represents flex size. It is only relevant if the parent of customScroll has display: flex. See example below.
  This prop will override any value given to heightRelativeToParent when setting the height of customScroll.
• onScroll - function, default undefined. Listener that will be called on each scroll.
• addScrolledClass : boolean, default false. If true, will add a css class 'content-scrolled' while being scrolled.
• freezePosition : boolean, default false. When true, will prevent scrolling.
• minScrollHandleHeight : number, sets the mimimum height of the scroll handle. Default is 38, as in Chrome on OSX.
• rtl : boolean, default false. Right to left document, will place the custom scrollbar on the left side of the content, and assume the native one is also there.
• scrollTo: number, default undefined. Will scroll content to the given value.
• keepAtBottom: boolean, default false. For dynamic content, will keep the scroll position at the bottom of the content, when the content changes, if the position was at the bottom before the change. See example here
• className: string, default undefined. Allows adding your own class name to the root element.
• handleClass: string. Can be used to replace the className given to the scroll handle, which is 'rcs-inner-handle' by default.

<CustomScroll heightRelativeToParent="calc(100% - 20px)">
  your content
</CustomScroll>  

• Check if you forgot to remove 'overflow' properties from the content root element.
• If you're using JSX, make sure you use Pascal case and not camelCase <CustomScroll> and not <customScroll>.
  starting with lower case causes JSX to treat the tag as a native dom element
• Make sure you have a height limit on the content root element (max-height)
• Check if your height limit is relative to parent, and you didn't use heightRelativeToParent prop.

• You can use CustomScroll types by installing @types/react-custom-scroll from npm

There are some details that apply when using customScroll on elements with size set by css flex.
Here is an example for an HTML structure before using customScroll:

<SomeParent style="display: flex; height: 500px;">
  <FixedHeightElement style="height: 100px"><FixedHeightElement />
  <FlexibleHeightElement style="flex:1; overflow:scroll">
    your content (with enough height to cause a scroll)
  <FlexibleHeightElement />
</SomeParent>  

In this example, a scroll is active on the flexibleHeightElement, where the flex size sets it's height to 400px, after the fixedHeight element took 100px.

There are 2 options to use customScroll with this structure:

• Wrapping the content:
  For this solution, the overflow property should be removed from the flex size element, since the customScroll will take care of that. Instead, min-height and min-width should be set to 0.

<someParent style="display: flex; height: 500px;">
  <fixedHeightElement style="height: 100px"><fixedHeightElement/>
  <flexibleHeightElement style="flex:1; min-height: 0; min-width: 0">
    <CustomScroll heightRelativeToParent="100%">
      your content (with enough height to cause a scroll)
    <CustomScroll/>
  <flexibleHeightElement/>
</someParent>  

min-height and min-width are required since flex won't shrink below it's minimum content size (flex box spec).

• Replacing the flex-size element with customScroll

<someParent style="display: flex; height: 500px;">
  <fixedHeightElement style="height: 100px"><fixedHeightElement/>
  <CustomScroll flex="1">
      your content (with enough height to cause a scroll)
  <CustomScroll/>
</someParent>  

This project is built using Vite. To run in dev mode - "yarn dev" or "npm run dev". To build the project - "yarn build" or "npm run build".

npm install
npm test
# Or for continuous run
npx karma start