07チェックサムカウントダウン

<main class="stage">
  <p class="cc-row">
    <span class="cc-text" aria-live="polite">
      <span class="cc-c">V</span><span class="cc-c">E</span><span class="cc-c">R</span><span class="cc-c">I</span><span class="cc-c">F</span><span class="cc-c">I</span><span class="cc-c">E</span><span class="cc-c">D</span>
    </span>
    <span class="cc-pct">0%</span>
  </p>
</main>

@use "../../../../site/static/demo-tokens" as *;

// ── 변수 3개 ──────────────────────────────────────────
$duration: $dur-loop;
$easing: $ease-pop;
$color: $subject-cream;

@include stage($stage-orange);

.cc-row {
  margin: 0;
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  align-items: baseline;
  gap: $sp-3;
}

.cc-text {
  display: inline-flex;
  gap: 0;
  font: 800 clamp(18px, 6vw, 26px)/1.2 "Space Mono", "Courier New", monospace;
  color: $color;
}

.cc-c { display: inline-block; min-width: 1ch; }

.cc-c.cc-pop { animation: cc-pop $easing 220ms; }

.cc-pct {
  font: 700 clamp(13px, 4vw, 17px)/1 "Space Mono", "Courier New", monospace;
  color: $subject-ink;   // 주황 무대 위 % 글자 — AA 4.5 (크림+opacity .8 은 2.45:1 이었다)
}

@keyframes cc-pop {
  0% { transform: scale(1.6); }
  100% { transform: scale(1); }
}

// 이 데모는 CSS keyframes 가 아니라 짧은 JS 로 밑줄을 글자로 채운다 —
// reduced-motion 은 스크립트 안의 matchMedia 체크로 처리한다 (index.html 참고)
@media (prefers-reduced-motion: reduce) {
  .cc-c, .cc-pct { color: $color; }
}

html, body {
  margin: 0;
  overflow: hidden;
}

.stage {
  box-sizing: border-box;
  min-height: 100vh;
  display: grid;
  place-items: center;
  margin: 0;
  background: #ff4d1f;
  font-family: -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  padding: clamp(8px, 4vw, 24px);
}

.cc-row {
  margin: 0;
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  align-items: baseline;
  gap: 12px;
}

.cc-text {
  display: inline-flex;
  gap: 0;
  font: 800 clamp(18px, 6vw, 26px)/1.2 "Space Mono", "Courier New", monospace;
  color: #fff7e6;
}

.cc-c {
  display: inline-block;
  min-width: 1ch;
}

.cc-c.cc-pop {
  animation: cc-pop cubic-bezier(0.2, 1.4, 0.4, 1) 220ms;
}

.cc-pct {
  font: 700 clamp(13px, 4vw, 17px)/1 "Space Mono", "Courier New", monospace;
  color: #17141a;
}

@keyframes cc-pop {
  0% {
    transform: scale(1.6);
  }
  100% {
    transform: scale(1);
  }
}
@media (prefers-reduced-motion: reduce) {
  .cc-c, .cc-pct {
    color: #fff7e6;
  }
}

var target = "VERIFIED";
  var spans = document.querySelectorAll(".cc-c");
  var pct = document.querySelector(".cc-pct");
  var reduced = window.matchMedia("(prefers-reduced-motion: reduce)").matches;
  var n = 0;
  setInterval(function () {
    n++;
    var filled = reduced ? target.length : Math.min(target.length, Math.floor((n % 50) / 5));
    spans.forEach(function (s, i) {
      s.textContent = i < filled ? target[i] : "_";
      s.classList.toggle("cc-pop", i === filled - 1);
    });
    pct.textContent = Math.round(filled / target.length * 100) + "%";
  }, 90);

import { useEffect, useRef, useState } from "react";
import styles from "./CountdownChecksum.module.scss";

export interface CountdownChecksumProps {
  text?: string;
  interval?: number;
}

// 실사용: 뷰포트에 들어오면 밑줄이 진행률에 맞춰 왼쪽부터 글자로 채워진다. 다 채우면 멈춘다.
export default function CountdownChecksum({ text = "VERIFIED", interval = 90 }: CountdownChecksumProps) {
  const ref = useRef<HTMLParagraphElement>(null);
  const [filled, setFilled] = useState(0);

  useEffect(() => {
    const el = ref.current;
    if (!el) return;
    let timer: ReturnType<typeof setInterval> | null = null;
    const io = new IntersectionObserver((entries) => {
      entries.forEach((entry) => {
        if (!entry.isIntersecting || timer) return;
        io.unobserve(entry.target);
        const reduced = window.matchMedia("(prefers-reduced-motion: reduce)").matches;
        if (reduced) { setFilled(text.length); return; }
        timer = setInterval(() => {
          setFilled((f) => {
            const next = f + 1;
            if (next >= text.length && timer) { clearInterval(timer); timer = null; }
            return Math.min(text.length, next);
          });
        }, interval);
      });
    }, { threshold: 0.3 });
    io.observe(el);
    return () => { io.disconnect(); if (timer) clearInterval(timer); };
  }, [text, interval]);

  return (
    <p ref={ref} className={styles.row} aria-live="polite">
      <span className={styles.text}>
        {text.split("").map((ch, i) => (
          <span key={i} className={i === filled - 1 ? styles.pop : undefined}>{i < filled ? ch : "_"}</span>
        ))}
      </span>
      <span className={styles.pct}>{Math.round((filled / text.length) * 100)}%</span>
    </p>
  );
}