Eye blink detection with tracking js?

Question

I am looking for pure java script solution for eye blink detection using tracking js or any other js lib. 70 to 80 % accuracy is fine for me.

Using Tracking js, With below code, I can get eye's bounding rectangle. Any ideas how to achieve blink detection?

  var tracker = new tracking.ObjectTracker( 'eye');
  tracker.setStepSize(1.7);

  tracking.track('#img', tracker);

  tracker.on('track', function(event) {
    event.data.forEach(function(rect) {
      // drawing rectangle on canvas
      window.plot(rect.x, rect.y, rect.width, rect.height);
    });
  });