To create custom animations with Konva, we can use the Konva.Animation
constructor which takes two arguments, the required update function and
an optional layer, or array of layers, that will be updated with each animation frame.
The animation function is passed a frame object which contains a time property which is the number
of milliseconds that the animation has been running, a timeDiff property which
is the number of milliseconds that have passed since the last frame,
and a frameRate property which is the current frame rate in frames per second.

The update function should never redraw the stage or a layer because the animation
engine will intelligently handle that for us.
The update function should only contain logic that updates Node properties,
such as position, rotation, scale, width, height, radius, colors, etc.
Once the animation has been created, we can start it at anytime with the start() method.

For a full list of attributes and methods, check out the Konva.Animation documentation.

HTML5 Canvas Konva Animation Template

<script>
  var anim = new Konva.Animation(function(frame) {
    var time = frame.time,
        timeDiff = frame.timeDiff,
        frameRate = frame.frameRate;

    // update stuff
  }, layer);

  anim.start();
</script>