app.js

let progress = document.getElementById("progress");
let song = document.getElementById("song");
let ctrlIcon = document.getElementById("ctrlIcon");

song.onloadedmetadata = function () {
  progress.max = song.duration;
  progress.value = song.currentTime;
};

function playPause() {
  if (ctrlIcon.classList.contains("fa-pause")) {
    song.pause();
    ctrlIcon.classList.remove("fa-pause");
    ctrlIcon.classList.add("fa-play");
  } else {
    song.play();
    ctrlIcon.classList.add("fa-pause");
    ctrlIcon.classList.remove("fa-play");
  }
}

if(song.play()){
    setInterval(() => {
        progress.value = song.currentTime
    }, 500)

}

progress.onchange = function(){
    song.play();
    song.currentTime = progress.value;
    ctrlIcon.classList.add('fa-pause');
    ctrlIcon.classList.remove('fa-play');
}