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07 Typewriter

Motion · Entrances
Typewriter

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motion-typewriter-everything.md

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Prompt

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Typewriter — Typewriter effect

Build a typewriter effect where three lines of text are typed one character at a time, in the order they enter the viewport. Line 1 is a bold heading at 32px, line 2 is body text at 20px in a muted colour, and line 3 is a heading again. Each line starts typing when 50% of it is inside the viewport's bottom edge, and adds one character every 80 milliseconds. A line starts only after the previous line has finished. While a line is being typed, show a blinking cursor 0.08em wide at its end, on a 1-second cycle with steps(1), and remove it when the line is done. Update textContent one character at a time in JavaScript, drive it with IntersectionObserver, and do not use any library.

Do not drop:
- Type lines in the order they enter the viewport; never start a line before the previous one finishes
- Keep the full text in the HTML so it reads without JavaScript
- With reduced motion, show the full text immediately with no cursor

A working example (one self-contained HTML file): https://design-vault.pages.dev/designs/motion-typewriter/demo.html

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demo.html

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/designs/motion-typewriter/demo.html — One self-contained HTML file. CSS and plain JavaScript only; it fetches nothing.

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<!doctype html>
<html lang="ja">
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<title>07 タイプライター — Typewriter effect</title>
<style>
/* dv-motion-base:start */
:root {
  --ground: #FFFFFF;
  --surface: #F3F5F8;
  --ink: #14181F;
  --muted: #5A6472;
  --accent: #1F5FA8;
  --rule: #D8DDE4;
  --accent-soft: color-mix(in srgb, var(--accent) 12%, var(--ground));
  --accent-mid: color-mix(in srgb, var(--accent) 45%, var(--ground));
  --shade: color-mix(in srgb, var(--ink) 14%, transparent);

  --font: "Zen Kaku Gothic New", "Hiragino Sans", "Noto Sans JP", "Yu Gothic", system-ui, sans-serif;
  --mono: ui-monospace, "SF Mono", Menlo, Consolas, monospace;

  --t-label: 13px;
  --t-body: 16px;
  --t-lead: 20px;
  --t-h2: 32px;
  --t-h1: clamp(40px, 7vw, 72px);

  --s1: 4px;
  --s2: 8px;
  --s3: 16px;
  --s4: 24px;
  --s5: 40px;
  --s6: 64px;
  --s7: 104px;

  --radius: 12px;
  --ease: cubic-bezier(.2, .7, .2, 1);
  --dur: .7s;
  --measure: 1080px;
}
*, *::before, *::after { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body {
  margin: 0;
  background: var(--ground);
  color: var(--ink);
  font-family: var(--font);
  font-size: var(--t-body);
  line-height: 1.7;
  font-feature-settings: "palt";
  overflow-x: hidden;
}
h1, h2, h3, p, ul, ol, figure { margin: 0; padding: 0; }
ul, ol { list-style: none; }
.dv-wrap { width: min(100% - 2 * var(--s4), var(--measure)); margin-inline: auto; }
.dv-label {
  min-height: 72vh;
  display: grid;
  align-content: center;
  gap: var(--s3);
  padding-block: var(--s6);
  border-bottom: 1px solid var(--rule);
}
.dv-num { font-family: var(--mono); font-size: var(--t-lead); font-weight: 700; color: var(--accent); letter-spacing: .04em; }
.dv-name { font-size: var(--t-h1); font-weight: 700; line-height: 1.15; letter-spacing: .01em; }
.dv-ai { font-family: var(--mono); font-size: var(--t-lead); color: var(--muted); }
.dv-desc { font-size: var(--t-lead); color: var(--ink); }
.dv-hint { font-size: var(--t-label); color: var(--muted); letter-spacing: .12em; margin-top: var(--s4); }
.dv-stage { padding-block: var(--s7); }
.dv-h2 { font-size: var(--t-h2); font-weight: 700; line-height: 1.3; }
.dv-lead { font-size: var(--t-lead); color: var(--muted); }
.dv-eyebrow { font-family: var(--mono); font-size: var(--t-label); color: var(--accent); letter-spacing: .12em; text-transform: uppercase; }
.dv-card { background: var(--surface); border: 1px solid var(--rule); border-radius: var(--radius); padding: var(--s4); }
.dv-ph {
  border-radius: var(--radius);
  background: linear-gradient(135deg, var(--accent-soft), var(--accent-mid) 60%, var(--accent));
  aspect-ratio: 16 / 9;
}
.dv-ph--alt { background: linear-gradient(200deg, var(--surface), var(--accent-soft) 55%, var(--accent-mid)); }
.dv-ph--ink { background: linear-gradient(160deg, var(--ink), color-mix(in srgb, var(--ink) 55%, var(--accent))); }
.dv-end {
  min-height: 60vh;
  display: grid;
  place-items: center;
  border-top: 1px solid var(--rule);
  color: var(--muted);
  font-family: var(--mono);
  font-size: var(--t-label);
  letter-spacing: .12em;
}
/* dv-motion-base:end */

/* ---- この演出だけの CSS。色は var(--…) か color-mix() のみ ---- */
.beat { min-height: 80vh; display: grid; align-content: center; }
.type { font-size: var(--t-h2); font-weight: 700; line-height: 1.4; min-height: 1.4em; }
.type--body { font-size: var(--t-lead); font-weight: 400; color: var(--muted); line-height: 1.8; min-height: 1.8em; }
.type.is-typing::after {
  content: "";
  display: inline-block;
  width: .08em;
  height: 1em;
  margin-left: .06em;
  vertical-align: -.12em;
  background: var(--ink);
  animation: dv-blink 1s steps(1) infinite;
}
@keyframes dv-blink { 50% { opacity: 0; } }

@media (prefers-reduced-motion: reduce) {
  .type.is-typing::after { display: none; }
}
</style>
</head>
<body data-motion-number="07">
<header class="dv-label">
  <div class="dv-wrap">
    <p class="dv-num">07</p>
    <h1 class="dv-name">タイプライター</h1>
    <p class="dv-ai">Typewriter effect</p>
    <p class="dv-desc">1文字ずつ打ち込まれる</p>
    <p class="dv-hint">SCROLL ↓</p>
  </div>
</header>

<main class="dv-stage">
  <section class="dv-wrap beat">
    <p class="type" data-type>見出しが入ります。</p>
  </section>
  <section class="dv-wrap beat">
    <p class="type type--body" data-type>本文のダミーです。画面に入ると、一文字ずつ打ち込まれて表示されます。</p>
  </section>
  <section class="dv-wrap beat">
    <p class="type" data-type>最後の一行も、同じように入ります。</p>
  </section>
</main>

<footer class="dv-end">END — 07 タイプライター</footer>

<script>
/* dv-motion-helpers:start */
const dvReduce = matchMedia('(prefers-reduced-motion: reduce)').matches;
document.documentElement.classList.add('js');

/**
 * 画面に入った要素へ .is-in を付ける。
 * data-reveal="repeat" の要素は画面を出たら外す(何度でも再生)。
 */
function dvReveal(selector = '[data-reveal]', { threshold = 0.2, rootMargin = '0px 0px -8% 0px' } = {}) {
  const els = [...document.querySelectorAll(selector)];
  if (dvReduce || !('IntersectionObserver' in window)) {
    els.forEach((el) => el.classList.add('is-in'));
    return;
  }
  const io = new IntersectionObserver((entries) => {
    for (const e of entries) {
      if (e.isIntersecting) {
        e.target.classList.add('is-in');
        if (e.target.dataset.reveal !== 'repeat') io.unobserve(e.target);
      } else if (e.target.dataset.reveal === 'repeat') {
        e.target.classList.remove('is-in');
      }
    }
  }, { threshold, rootMargin });
  els.forEach((el) => io.observe(el));
}

/**
 * スクロール量を 0〜1 にして、各 [data-progress] 要素の CSS 変数 --p に書く。
 *   data-progress="through" : 要素の上端が画面の下端に来たとき 0、下端が画面の上端を抜けたとき 1
 *   data-progress="pin"     : 要素の上端が画面の上端に来たとき 0、下端が画面の下端に来たとき 1
 *                             (中に position: sticky の箱を持つ、背の高い区画用)
 *   data-progress="page"    : ページ全体のスクロール量
 * onUpdate(el, p) を渡すと、値が変わるたびに呼ばれる。
 */
function dvProgress(onUpdate) {
  const els = [...document.querySelectorAll('[data-progress]')];
  const clamp = (n) => Math.min(1, Math.max(0, n));
  let queued = false;
  const measure = () => {
    queued = false;
    const vh = window.innerHeight;
    for (const el of els) {
      const r = el.getBoundingClientRect();
      let p;
      if (el.dataset.progress === 'pin') p = r.height > vh ? -r.top / (r.height - vh) : 0;
      else if (el.dataset.progress === 'page') {
        const max = document.documentElement.scrollHeight - vh;
        p = max > 0 ? window.scrollY / max : 0;
      } else p = (vh - r.top) / (vh + r.height);
      p = clamp(p);
      el.style.setProperty('--p', p.toFixed(4));
      if (onUpdate) onUpdate(el, p);
    }
  };
  const request = () => {
    if (!queued) { queued = true; requestAnimationFrame(measure); }
  };
  addEventListener('scroll', request, { passive: true });
  addEventListener('resize', request);
  measure();
}
/* dv-motion-helpers:end */

/* ---- この演出だけの JS ---- */
const typed = [...document.querySelectorAll('[data-type]')];
if (!dvReduce && 'IntersectionObserver' in window) {
  const texts = new Map(typed.map((el) => [el, el.textContent]));
  typed.forEach((el) => { el.textContent = ''; });

  const typeOne = (el) => new Promise((done) => {
    const chars = [...texts.get(el)];
    let i = 0;
    el.classList.add('is-typing');
    const step = () => {
      el.textContent = chars.slice(0, ++i).join('');
      if (i < chars.length) setTimeout(step, 80);
      else { el.classList.remove('is-typing'); done(); }
    };
    setTimeout(step, 80);
  });

  // 行は画面に入った順に、前の行が打ち終わってから打つ。
  let queue = Promise.resolve();
  const io = new IntersectionObserver((entries) => {
    for (const e of entries) {
      if (!e.isIntersecting) continue;
      io.unobserve(e.target);
      queue = queue.then(() => typeOne(e.target));
    }
  }, { threshold: 0.5 });
  typed.forEach((el) => io.observe(el));
}
</script>
</body>
</html>

/ai/assets/motion-typewriter.json