SoundCloud: cambia velocità di riproduzione

// SoundCloud: cycle the audio playback speed 1x to 1.25x to 1.5x to 2x.
(function () {
  var steps = [1, 1.25, 1.5, 2];
  var media = document.querySelector('audio, video');
  if (!media) { alert('No SoundCloud audio is playing right now.'); return; }
  var i = steps.indexOf(media.playbackRate);
  var next = steps[(i + 1) % steps.length];
  try {
    media.playbackRate = next;
    alert('Playback speed set to ' + next + 'x.');
  } catch (e) {
    alert('Could not change playback speed: ' + e.message);
  }
})();