let playNum = 0;
const playList = [{title: 'Aqua Caelestis'}, {title: 'Aqua Caelestis'}, {title: 'Aqua Caelestis'}]
playNext.addEventListener("click", function playNext(e) {
if (playNum === 0) {
playNum = 0;
} else if (playList.length >= playNum) {
playNum++;
} else {
playNum = 0;
}
});