Random-order Reveal

<script src="https://cdn.jsdelivr.net/npm/[email protected]/dist/bundles/anime.umd.min.js"></script>
<script>
  (function () {
    // Random-order Reveal: letters blink into place in a shuffled order, each
    // one flashing a highlight colour as it lands, until the whole line is there.
    // Usage: <h1 data-random-order-reveal>Pieced together</h1>
    // Optional: data-loop (letters vanish in a new order and reappear in
    // another), data-hold (ms to stay before vanishing), data-color (flash
    // colour; default #a855f7), data-duration (ms per letter), data-stagger (ms
    // between letters), data-delay (ms before starting).
    var DEFAULTS = { color: '#a855f7', duration: 700, stagger: 45, delay: 0, hold: 1800 };

    var css =
      '.ror-word{display:inline-block;white-space:nowrap}' +
      '.ror-char{display:inline-block;will-change:transform,opacity}';
    var style = document.createElement('style');
    style.textContent = css;
    document.head.appendChild(style);

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

    function split(el) {
      var text = el.textContent.replace(/\s+/g, ' ').trim();
      el.setAttribute('aria-label', text);
      el.textContent = '';
      var chars = [];
      text.split(' ').forEach(function (word, i) {
        if (i) el.appendChild(document.createTextNode(' '));
        var w = document.createElement('span');
        w.className = 'ror-word';
        w.setAttribute('aria-hidden', 'true');
        Array.from(word).forEach(function (c) {
          var s = document.createElement('span');
          s.className = 'ror-char';
          s.textContent = c;
          w.appendChild(s);
          chars.push(s);
        });
        el.appendChild(w);
      });
      return chars;
    }

    // A fresh random order every time (Fisher-Yates).
    function shuffled(list) {
      var a = list.slice();
      for (var i = a.length - 1; i > 0; i--) {
        var j = Math.floor(Math.random() * (i + 1));
        var t = a[i]; a[i] = a[j]; a[j] = t;
      }
      return a;
    }

    function play(el, chars) {
      var d = el.dataset;
      var loop = d.loop !== undefined && d.loop !== 'false';
      var duration = +d.duration || DEFAULTS.duration;
      var stagger = +d.stagger || DEFAULTS.stagger;
      var hold = +d.hold || DEFAULTS.hold;
      var color = d.color || DEFAULTS.color;
      var base = getComputedStyle(el).color;

      function reveal() {
        // The stagger follows the order of the list, so shuffling it shuffles
        // the order the letters arrive in.
        anime.animate(shuffled(chars), {
          opacity: { from: 0, to: 1, duration: duration * 0.25, ease: 'linear' },
          scale: [1.45, 1],
          color: [color, base],
          duration: duration,
          ease: 'out(3)',
          delay: anime.stagger(stagger),
          onComplete: loop ? function () { setTimeout(vanish, hold); } : undefined
        });
      }
      function vanish() {
        anime.animate(shuffled(chars), {
          opacity: 0,
          scale: 0.8,
          duration: duration * 0.35,
          ease: 'in(2)',
          delay: anime.stagger(stagger * 0.6),
          onComplete: function () { setTimeout(reveal, 400); }
        });
      }
      setTimeout(reveal, +d.delay || DEFAULTS.delay);
    }

    function init() {
      var io = new IntersectionObserver(function (entries) {
        entries.forEach(function (e) {
          if (!e.isIntersecting) return;
          io.unobserve(e.target);
          play(e.target, e.target._rorChars);
        });
      }, { threshold: 0.2 });
      document.querySelectorAll('[data-random-order-reveal]').forEach(function (el) {
        if (el._rorChars) return;
        var chars = split(el);
        el._rorChars = chars;
        if (reduced()) return;
        anime.utils.set(chars, { opacity: 0 });
        io.observe(el);
      });
    }

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

<h1 data-random-order-reveal>Pieced together</h1>

<!-- a yellow flash, looping: -->
<h1 data-random-order-reveal data-color="#facc15" data-loop>Pieced together</h1>