Count down timer

HTML

<div id="countdown"></div>
<input type="text" placeholder = "seconds" id="seconds"/>
<button id="btn-timer">Set Timer</button>

JavaScript

var seconds;
  var temp;
 
  function countdown() {
    seconds = document.getElementById('seconds').value;
    seconds = parseInt(seconds, 10);
 
    if (seconds == 1) {
      temp = document.getElementById('countdown');
      temp.innerHTML = "all done, bye bye";
      return;
    }
 
    seconds--;
    temp = document.getElementById('countdown');
    temp.innerHTML = seconds;
    timeoutMyOswego = setTimeout(countdown, 1000);
  }