Character Skew-in

<script src="https://cdn.jsdelivr.net/npm/[email protected]/dist/bundles/anime.umd.min.js"></script>
<script>
  (function () {
    // Character Skew-in: letters slide in from the right leaning hard, then
    // snap upright as they land, overshooting the lean a little the other way.
    // Usage: <h1 data-character-skew-in>Lean into it</h1>
    // Optional: data-loop (letters lean away to the left and slide in again),
    // data-hold (ms to stay before leaving), data-skew (degrees of lean at the
    // start; default 40), data-distance (how far they slide, in em; default
    // 1.2), data-duration (ms per letter), data-stagger (ms between letters),
    // data-delay (ms before starting).
    var DEFAULTS = { skew: 40, distance: 1.2, duration: 1000, stagger: 40, delay: 0, hold: 1600 };

    var css =
      '.csk-word{display:inline-block;white-space:nowrap}' +
      '.csk-char{display:inline-block;transform-origin:50% 100%;will-change:transform}';
    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 = 'csk-word';
        w.setAttribute('aria-hidden', 'true');
        Array.from(word).forEach(function (c) {
          var s = document.createElement('span');
          s.className = 'csk-char';
          s.textContent = c;
          w.appendChild(s);
          chars.push(s);
        });
        el.appendChild(w);
      });
      return chars;
    }

    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 skew = +d.skew || DEFAULTS.skew;
      var distance = +d.distance || DEFAULTS.distance;

      var tl = anime.createTimeline({ loop: loop, loopDelay: 300, delay: +d.delay || DEFAULTS.delay });
      tl.add(chars, {
        // Slanted like italics while moving, the tops trailing behind, then
        // whipped upright (and a touch past) as they land.
        x: { from: distance + 'em', to: '0em', ease: 'outExpo' },
        skewX: { from: -skew, to: 0, ease: 'outBack(2.2)' },
        opacity: { from: 0, to: 1, duration: duration * 0.35, ease: 'linear' },
        duration: duration,
        delay: anime.stagger(stagger)
      });
      if (loop) {
        tl.add(chars, {
          x: -distance + 'em',
          skewX: -skew,
          opacity: 0,
          duration: duration * 0.5,
          ease: 'in(3)',
          delay: anime.stagger(stagger * 0.6)
        }, '+=' + (+d.hold || DEFAULTS.hold));
      }
    }

    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._cskChars);
        });
      }, { threshold: 0.2 });
      document.querySelectorAll('[data-character-skew-in]').forEach(function (el) {
        if (el._cskChars) return;
        var chars = split(el);
        el._cskChars = 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-character-skew-in>Lean into it</h1>

<!-- or, leaning harder and looping: -->
<h1 data-character-skew-in data-skew="55" data-loop>Lean into it</h1>