web-scroller/web-scroller.js

'use strict';

(async ( ) => {

  const TOP_MARGIN = 0;      // set to top margin you want for the page scroller
  const SCROLL_SPEED = 2;    // number of pixels to scroll per frame
  const START_DELAY_MS = 0;   // set startup delay in milliseconds
  const HEIGHT = 200000;    // set to max distance you want to scroll

  let y = TOP_MARGIN;
  let paused = false;
  
  function update ( ) {
    try {
      if (!paused) {
        window.scrollTo(0, y);
        y += SCROLL_SPEED;
      }
      if (y < HEIGHT) {
        window.requestAnimationFrame(update);
      }
    } catch (error) {
      console.log('update has failed', error);
    }
  }

  try {
    window.scrollTo(0, y);
    window.setTimeout(update, START_DELAY_MS);  
  } catch (error) {
    console.log('scroller has failed', error);
  }

})();