if true load function

I want to do something like this: " if isPlaying = false;" ------>" function nextTrack() "and "function previousTrack()" ------> only " loadTrack(track_index);" and dont "playTrack();" --------> else loadTrack(track_index);" and "playTrack();"

How can I do it? Please help , I'm a newbie.... Thanks!

 let playpause_btn = document.querySelector(".playpause-track");
    let next_btn = document.querySelector(".next-track");
    let prev_btn = document.querySelector(".prev-track");


    let track_index = 0;
    let isPlaying = false;
 
 
 
 
 function playpauseTrack() {
      if (!isPlaying) playTrack();
      else pauseTrack();
    }

    function playTrack() {
      curr_track.play();
      isPlaying = true;   
  }
    
    function pauseTrack() {
      curr_track.pause();
      isPlaying = false;
  }

    function nextTrack() {
      if (track_index < track_list.length - 1) 
        track_index += 1;
      else track_index = 0;
        loadTrack(track_index);
       playTrack();    
    }

    function prevTrack() {
      if (track_index > 0)
        track_index -= 1;
      else track_index = track_list.length;
      loadTrack(track_index);
      playTrack();
    }