Polling for track positon with SoundCloud JS api

Polling for track positon

var positionInterval;
var startPolling = function(player) {
  positionInterval = setInterval(function() {
    var trackPosition = player.api_getTrackPosition();
    // do something with the trackPosition
  }, 500);
};
var stopPolling = function() {
  clearInterval(positionInterval);
  positionInterval = null;
};

soundcloud.addEventListener('onMediaStart', function(player, data) {
  startPolling(player);
});

soundcloud.addEventListener('onMediaEnd', function(player, data) {
  stopPolling();
});