Why can't JavaScript .play() audio files on iPhone safari?

I've got a JavaScript web app working that plays some audio periodically like this:

var SOUND_SUCCESS = new Audio('success.mp3');
SOUND_SUCCESS.play();

This works great on desktop browsers (tested in Edge and Chrome), but it doesn't play on Safari on iPhone.

I've looked around Stack Overflow, and I found some answers from a couple of years ago that it's not possible to play audio from Safari unless you're in that full screen player. Is this still the case?