code: function bounce(t) {
    const s = 7.5625;
    const p = 2.75;
    let l;
    if (t < (1 / p)) {
      l = s * t * t;
    } else {
      if (t < (2 / p)) {
        t -= (1.5 / p);
        l = s * t * t + 0.75;
      } else {
        if (t < (2.5 / p)) {
          t -= (2.25 / p);
          l = s * t * t + 0.9375;
        } else {
          t -= (2.625 / p);
          l = s * t * t + 0.984375;
        }
      }
    }
    return l;
  }
docs: A bounce easing method (from https://github.com/DmitryBaranovskiy/raphael).