How to get the exact smooth scrolling functionality of Chrome?

When the user clicks a button on my page it creates a new element below it and then scrolls downwards towards it. I'd like this to be done smoothly, and that can be accomplished like so:

window.scroll({ top: document.body.scrollHeight, behavior: "smooth" });

However, this does not work on Safari, so it appears that I need to use a custom function instead to get this functionality.

I searched around and found this (current answer, but suboptimal):

doScrolling = (elementY, duration) => { 
  let startingY = window.pageYOffset;
  let diff = elementY - startingY;
  var start;

  // Bootstrap our animation - it will get called right before next frame shall be rendered.
  window.requestAnimationFrame(function step(timestamp) {
    if (!start) { start = timestamp; }
    // Elapsed milliseconds since start of scrolling.
    let time = timestamp - start;
    // Get percent of completion in range [0, 1].
    let percent = Math.min(time / duration, 1);

    window.scrollTo(0, startingY + diff * percent);

    let isScrollAtBottom = (window.innerHeight + window.pageYOffset) >= document.body.scrollHeight - 3;

    if (isScrollAtBottom) { return; }

    // Proceed with animation as long as we wanted it to.
    if (time < duration) {
      window.requestAnimationFrame(step);
    }
  })
}

Called like: this.doScrolling(document.body.scrollHeight, 750);

Which seems to work, but it doesn't seem to have the same semantics as window.scroll.

For one, you need to specify a duration, whereas with window.scroll it's implied.

Secondly, it seems as if window.scroll uses a different transition type? It's hard to tell, but it feels more like an ease as opposed to a linear transition, where it starts off slow, then goes fast, and then slows to a stop.

Is it possible to modify the above function to mimic the exact semantics of window.scroll such that you can't tell the difference between calling the two?

To clarify, I don't need to clone all the functionalities of window.scroll. The only thing I require is the ability to scroll to a given position (in my case it's always the end of the page) in a smooth manner. The function I provided above in my question is almost perfect, except that it's slightly janky and doesn't feel as smooth as window.scroll. I think it may be the animation style? It's kind of hard to tell why it looks "worse" since it's so fast.

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