Back In

<script src="https://cdn.jsdelivr.net/npm/[email protected]/dist/bundles/anime.umd.min.js"></script>
<script>
  (function () {
    // Back In: the element approaches from off screen at reduced size, as if
    // from a distance, then grows to full size once it's in place.
    // Usage: <div data-back-in>…</div>
    // It starts just past the edge of the nearest container that clips its
    // overflow (overflow: hidden or clip), or of the window.
    // Optional: data-from ("top", default, "bottom", "left" or "right"; give
    // several, like "top right left", and each loop uses the next),
    // data-distance (px to travel instead of from off screen), data-scale (its
    // size on the way in, default 0.7), data-duration (ms, default 1200),
    // data-delay (ms before the first entrance), data-loop (hold, fade away
    // and come in again), data-hold (ms to stay when looping, default 1400).
    var DEFAULTS = { from: 'top', scale: 0.7, duration: 1200, delay: 0, hold: 1400 };

    function reduced() {
      return window.matchMedia('(prefers-reduced-motion: reduce)').matches;
    }

    // The box the element must leave to be "off screen".
    function clipBox(el) {
      for (var p = el.parentElement; p && p !== document.body; p = p.parentElement) {
        var s = getComputedStyle(p);
        if (s.overflowX !== 'visible' || s.overflowY !== 'visible') return p.getBoundingClientRect();
      }
      return { left: 0, top: 0, right: window.innerWidth, bottom: window.innerHeight };
    }

    // Where to start: an x/y offset that puts the element just outside the box.
    function offset(el, from) {
      var d = +el.dataset.distance;
      var r = el.getBoundingClientRect();
      var c = clipBox(el);
      if (from === 'right') return { x: d || c.right - r.left + 8, y: 0 };
      if (from === 'left') return { x: -(d || r.right - c.left + 8), y: 0 };
      if (from === 'bottom') return { x: 0, y: d || c.bottom - r.top + 8 };
      return { x: 0, y: -(d || r.bottom - c.top + 8) };
    }

    function enter(el, from, done) {
      var d = el.dataset;
      var t = +d.duration || DEFAULTS.duration;
      var o = offset(el, from);
      anime.utils.set(el, { x: o.x, y: o.y, scale: +d.scale || DEFAULTS.scale, opacity: 0.7 });
      anime.createTimeline({ onComplete: done })
        // Glide in while still small and far away...
        .add(el, { x: 0, y: 0, opacity: 1, duration: t * 0.6, ease: 'out(3)' })
        // ...then step forward to full size.
        .add(el, { scale: 1, duration: t * 0.4, ease: 'outBack(1.3)' });
    }

    function cycle(el) {
      var d = el.dataset;
      var s = el._bki;
      var froms = (d.from || DEFAULTS.from).split(/[\s,]+/);
      enter(el, froms[s.n++ % froms.length], function () {
        if (d.loop === undefined || d.loop === 'false') return;
        setTimeout(function () {
          anime.animate(el, {
            opacity: 0,
            duration: 400,
            ease: 'out(2)',
            onComplete: function () {
              // Wait until it's back on screen before the next entrance.
              setTimeout(function () {
                if (s.visible) cycle(el);
                else s.waiting = true;
              }, 500);
            }
          });
        }, +d.hold || DEFAULTS.hold);
      });
    }

    function init() {
      var io = new IntersectionObserver(function (entries) {
        entries.forEach(function (e) {
          var s = e.target._bki;
          s.visible = e.isIntersecting;
          if (!e.isIntersecting) return;
          if (!s.started) {
            s.started = true;
            setTimeout(function () { cycle(e.target); }, +e.target.dataset.delay || DEFAULTS.delay);
          } else if (s.waiting) {
            s.waiting = false;
            cycle(e.target);
          }
        });
      }, { threshold: 0.2 });
      document.querySelectorAll('[data-back-in]').forEach(function (el) {
        if (el._bki) return;
        el._bki = { n: 0 };
        if (reduced()) return;
        anime.utils.set(el, { opacity: 0 });
        io.observe(el);
      });
    }

    if (document.readyState === 'loading') document.addEventListener('DOMContentLoaded', init);
    else init();
  })();
</script>

<div class="card" data-back-in>Reminder</div>

<!-- or from the left: -->
<div class="card" data-back-in data-from="left">Reminder</div>