Safari doesn't support the behaviour property when calling window.scroll. This prevents smooth scrolling. Copy and paste this code into your JS console to get smooth scrolling. Great for screen capture videos.

autoscroll.js

const footerHeight = 800;

let pos = 0,
  pageHeight = document.body.offsetHeight,
  winHeight = window.innerHeight,
  maxPos = pageHeight - winHeight - footerHeight;

function scrollWin() {
  if (pos >= maxPos) {
    console.log(`We're done at ${pos}`);
    return; // bailout
  }

  pos += 20;

  window.scroll({
    top: pos,
    left: 0,
  });

  setTimeout(scrollWin, 20)
}

// We need time to close the console
setTimeout(scrollWin, 5000);