Use requestAnimationFrame to handle scrolling smoothly

createScrollManager.js

const createScrollManager = function() {
  let callbacks = [];
  let scrollPosition = -1;
  let animatedKilled = false;
  
  const animate = () => {
    requestAnimationFrame(onScroll);
  }

  function onScroll(){
    if(animatedKilled) return;
 
    if (scrollPosition !== window.pageYOffset) {
      window.removeEventListener('scroll', animate);
      scrollPosition = window.pageYOffset;
      callbacks.forEach(cb => cb(scrollPosition));
      animate();
    } else {
      window.addEventListener('scroll', animate);
    }
  }
  
  animate();
  
  return {
    add: function(cb) {
      callbacks = [...callbacks, cb];
    },
    remove: function(cb) {
      callbacks = callbacks.filter(value => value != cb);
    },
    destroy: function() {
      animatedKilled = true;
      window.removeEventListener('scroll', animate);
    }
  }
}

export default createScrollManager;

About

To achieve smooth scrolling, we use request animation frame. To avoid calling this unnecessarily, we use scroll event listeners to start the animation loop if the user hasn't scrolled or has stopped scrolling.

Codepen Demo

Basic Usage

Create a Scroll Manager, ideally one per page, using createScrollManager().

• add(callback: function(scrollPosition) - Add a callback function to be fired every animation loop.
• remove(callback: function) - Remove a callback function from the Scroll Manager
• destroy() - Kill the Scroll Manager

const log1 = console.log.bind(null, 1);
const log2 = console.log.bind(null, 2);
const log3 = console.log.bind(null, 3);

const scrollManager = createScrollManager();

scrollManager.add(log1);
scrollManager.add(log2);
scrollManager.add(log3);

scrollManager.remove(log1);

setTimeout(scrollManager.destroy, 5000);

Inspired from this gist: https://gist.github.com/Warry/4254579

Would be nice if this could work with resize too, like scrollManager.add("resize", log1) and scrollManager.add("scroll", log1)