Smooth Scrolling with React & Framer Motion

Scrolling through a website especially with a notched mouse wheel is typically jumpy and harder to navigate.

Smooth Scrolling, or spring scrolling adds an animated touch to the traditional mouse scroll.

If you've never experienced smooth scrolling before, try out the Live Demo.

Concept

Consider the viewport window. When a bunch of HTML elements combine to a size taller than the window, it overflows and can be accessed when you scroll down.

To override the default scroll, we need to wrap the content in a fixed element we can control.

Finally, we will create an invisible spacer (div) equal to the scroll height of the content. This will trigger the browser's default scroll bar.

Setup

Create a React Typescript Repl on Replit to get started.

Install Framer Motion with npm install framer-motion.

The Component

The <SmoothScroll/> Component will wrap all the HTML elements we want to incorporate in the Smooth Scrolling effect.

export default function SmoothScroll({
  children
}: {
  children: React.ReactNode;
}) {
  return <></>;
}

Scroll & Spring Values

Import the following hooks from framer-motion.

import { useScroll, useSpring, useTransform } from 'framer-motion';

In the SmoothScroll component, destructure scrollYProgress from the useScroll hook.

const { scrollYProgress } = useScroll();

Next, use the useSpring hook to apply the smooth effect to the scrollYProgress value.

const smoothProgress = useSpring(scrollYProgress, { mass: 0.1 })

Content & Spacer

Add the motion component to the existing import from framer-motion.

- import { useScroll, useSpring } from 'framer-motion';
+ import { motion, useScroll, useSpring } from 'framer-motion';

Skip down to the component's return statement. Return an empty <div> element and a <motion.div> element which renders the children prop as a child.

return <>
  <div style={{ height: contentHeight }} />

  <motion.div
    className="scrollBody"
  >
    {children}
  </motion.div>
</>

Create a contentRef react reference via the useRef hook and a contentHeight state with useState.

import { useState, useRef } from 'react';

...

const contentRef = useRef<HTMLDivElement>(null);
const [contentHeight, setContentHeight] = useState(0);

Assign the content wrapper the contentRef.

<motion.div
  className="scrollBody"
  ref={contentRef}
>
  {children}
</motion.div>

Use the style prop to make the spacer have a height of contentHeight.

<div style={{ height: contentHeight }} />

Resize Handler

When the window gets resized, the height of the content content is likely to change. Since the contentHeight value is a state, we will need to update it whenever the window resizes, and when the contentRef reference updates.

Start by importing the useEffect hook from react.

- import { useState, useRef } from 'react';
+ import { useEffect, useState, useRef } from 'react';

Within the useEffect hook, create and call a handler to set the contentHeight value to contentRef.current.scrollHeight.

Add contentRef to the dependency array.

useEffect(() => {
  const handleResize = () => {
    if (contentRef.current) {
      setContentHeight(contentRef.current.scrollHeight)
    }
  }

  handleResize();
}, [contentRef]);

Finally, add a resize event listener to window in the useEffect hook, and return a disposer function.

useEffect(() => {
  ...

  window.addEventListener("resize", handleResize);

  return () => {
    window.removeEventListener("resize", handleResize);
  }
}, [contentRef, children]);

Put it all together

Import the useTransform hook from framer-motion.

- import { motion, useScroll, useSpring } from 'framer-motion';
+ import { useTransform, motion, useScroll, useSpring } from 'framer-motion';

Create a constant y and set it to the useTransform hook with smoothProgress as the initial value.

const y = useTransform(smoothProgress, value => {
  return value;
});

Visualizing how to calculate the scroll, we will be subtracting the viewport height from the content container's scroll height, multiplying it by -1, and then by value.

const y = useTransform(smoothProgress, value => {
  return value * -(contentHeight - window.innerHeight);
});

Use the y transformed value in the content container.

<motion.div

  className="scrollBody"

  style={{ y }}

  ref={contentRef}

>

  {children}

</motion.div>

Styles

I already fought CSS so you won't have to. Simply copy and paste the bare minimum CSS over and the scroll component will be ready to roll.

.scrollBody {

  width: 100vw;

  position: fixed;

  top: 0;

display: flex;

  flex-direction: column;

}

Complete 🎉

That's it! All you have to do is add a bunch of HTML elements within the <SmoothScroll /> component.

Nothing better than fifty <h1>Lorem Ipsum</h1>s in your codebase.

• Source Code: https://replit.com/@IroncladDev/FramerSmoothScroll?v=1
• Live Demo: https://framersmoothscroll.ironcladdev.repl.co

Thanks for reading. If you have any feedback or recommendations for this article, I'd love to hear it in the comments.

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