docs: function() {
            // Display the duration.
            duration.innerHTML = self.formatTime(Math.round(sound.duration()));
  
            // Start upating the progress of the track.
            requestAnimationFrame(self.step.bind(self));
  
            // Start the wave animation if we have already loaded
            wave.container.style.display = 'block';
            bar.style.display = 'none';
            pauseBtn.style.display = 'block';
          }