Function timeline

A "Timeline" modifies value of objects over time.

Timeline -> Property (prop) -> Set Constant (value) -> Perform Transition (ease)

To create the required objects we use a builder pattern like this:

const inAnimation = timeline
 .mark("t1", 0)
 .mark("t2", "80%")
 .mark("end", 4)
 .prop(() => obj.transform.identity())   // << always called
 .prop((x, y) => obj.transform.scale(x, y), "scale")
    .value("t1", [0, 0])
    .value("t2", [1, 1])
    .ease("t2", "end", [1, 1], [4, 4], Easing.Elastic.easeIn)
 .prop(v => obj.mixColor.alpha = v, "alpha")
    .ease(0, "100%", 0, 1)
 .prop(count => obj.text = "" + Math.round(count), "count")
    .ease(0, "100%", 0, 10)
 .done(2) // << duration must be called to finish the timeline

const fadeOut = timeline
  .read(inAnimation)
  .prop("alpha")
     .ease(0, 1, )