Why doesn't a setting a var to renderInElements on the buttons work?

var playlist = new Playlist()

var takeBackThisCity = new Song('Take Back This City', 'Snow Patrol', '4:23');
var intro = new Song ('Intro', 'The XX', '6:54');

playlist.add(takeBackThisCity);
playlist.add(intro);

var playlistElement = document.getElementById('playlist');
var refreshElements = playlist.renderInElement(playlistElement);


refreshElements;

var playButton = document.getElementById('play');
playButton.onclick = function() {
  playlist.play();
  refreshElements;
}
var nextButton = document.getElementById('next');
nextButton.onclick = function() {
  playlist.next();
  refreshElements;
}
var stopButton = document.getElementById('stop');
stopButton.onclick = function() {
  playlist.stop();
  refreshElements;
}

//...

playlist.renderInElement(playlistElement);

var playButton = document.getElementById('play');
playButton.onclick = function() {
  playlist.play();
  playlist.renderInElement(playlistElement);
}
var nextButton = document.getElementById('next');
nextButton.onclick = function() {
  playlist.next();
  playlist.renderInElement(playlistElement);
}
var stopButton = document.getElementById('stop');
stopButton.onclick = function() {
  playlist.stop();
  playlist.renderInElement(playlistElement);
}