← Entrances

Bounce In

The element pops in from small with a springy bounce: it overshoots, wobbles back and settles at full size. Turn the springiness up or down to suit.

Achievement unlockedSeven-day streak

How to use it

  1. Paste the snippet just before </head>.
  2. Add data-bounce-in to any element.

Options

Add any of these attributes to the same element.

data-scaleThe size it starts at. Default 0.3.
data-bounceHow springy, from 0 (one soft overshoot) to 1 (lively wobbles). Default 0.5.
data-durationHow long the bounce takes. Default 1100 ms.
data-delayWait before the first entrance. Default 0 ms.
data-loopHold, fade away and pop in again.
data-holdHow long it stays before fading, when looping. Default 1400 ms.
1 · Snippet
<script src="https://cdn.jsdelivr.net/npm/[email protected]/dist/bundles/anime.umd.min.js"></script>
<script>
  (function () {
    // Bounce In: the element pops in from small with a springy scale bounce,
    // overshooting and wobbling a little before it settles at full size.
    // Usage: <div data-bounce-in>…</div>
    // Optional: data-scale (the size it starts at, default 0.3), data-bounce
    // (how springy, 0 to 1, default 0.5), data-duration (ms, default 1100),
    // data-delay (ms before the first entrance), data-loop (hold, fade away
    // and pop in again), data-hold (ms to stay when looping, default 1400).
    var DEFAULTS = { scale: 0.3, bounce: 0.5, duration: 1100, delay: 0, hold: 1400 };

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

    function enter(el, done) {
      var d = el.dataset;
      var duration = +d.duration || DEFAULTS.duration;
      var bounce = d.bounce === undefined ? DEFAULTS.bounce : Math.min(1, Math.max(0, +d.bounce || 0));
      // A shorter elastic period means quicker, livelier wobbles.
      var period = (0.9 - bounce * 0.6).toFixed(2);
      anime.utils.set(el, { scale: d.scale === undefined ? DEFAULTS.scale : +d.scale, opacity: 0 });
      anime.animate(el, {
        scale: { to: 1, ease: 'outElastic(1, ' + period + ')' },
        opacity: { to: 1, duration: duration * 0.2, ease: 'linear' },
        duration: duration,
        onComplete: done
      });
    }

    function cycle(el) {
      var d = el.dataset;
      var s = el._bni;
      enter(el, 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._bni;
          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-bounce-in]').forEach(function (el) {
        if (el._bni) return;
        el._bni = { 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>
2 · Your HTML
<div class="badge" data-bounce-in>Achievement unlocked</div>

<!-- or extra springy: -->
<div class="badge" data-bounce-in data-bounce="0.9">Achievement unlocked</div>