Create scrolling digital typewriter text

I probably missed the most important feature:
the ability to pause and play the animation.
You might want to add a checkbox control ("Pause / Play") for this function.

source text expression:

spd = effect("TypeWrite Speed")(1);
s = effect("Pause / Play")(1);
t = time;

if (s.numKeys) {
  key = s.nearestKey(time).index;
  if (time < s.key(key).time) key--;
  
  if (key) {
    pause = 0;
    for (var i = 2; i <= key; i += 2) {
      pause += s.key(i).time - s.key(i - 1).time;
    }
    t = key % 2 === 1 ? s.key(key).time - pause : t - pause;
  }
}

text.sourceText.substr(0, t * spd);