05最終保存時刻の更新 — 保存が終わってから経過した時間の値が毎秒再計算され、文言に変わる方式

<main class="stage">
<div class="str is-demo" id="str">
  <span class="str__dot" id="strDot"></span>
  <span class="str__label" id="strLabel">たった今保存</span>
  <button class="str__btn" id="strBtn" type="button">今すぐ保存</button>
</div>
</main>

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

// 계산 겹: 경과 초 = (지금−저장시각)÷가속ms, 초·분 환산 문구 + 신선도 투명도 = 1−min(1,경과÷기준) — index.html 참조
@include stage($stage-yellow);

.str {
  display: flex;
  align-items: center;
  gap: $sp-2;
  padding: $sp-3 $sp-5;
  border-radius: $r-pill;
  background: $stage-ink;
}

.str__dot {
  width: $sp-2;
  height: $sp-2;
  border-radius: $r-pill;
  background: $subject-mint;
  flex: 0 0 auto;
}

.str__label {
  font: 600 14px/1 -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  color: $subject-cream;
  min-width: 128px;
}

.str__btn {
  margin-left: $sp-2;
  border: 0;
  border-radius: $r-control;
  padding: $sp-1 $sp-3;
  background: $subject-cream;
  color: $stage-ink;
  font: 700 12px/1 -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  cursor: pointer;
  transition: transform $dur-instant $ease-out;

  &:active { transform: scale(.96); }
}

@media (max-width: 340px) {
  .str { padding: $sp-2 $sp-4; flex-wrap: wrap; justify-content: center; }
  .str__label { font-size: 12px; min-width: 96px; }
}

@media (prefers-reduced-motion: reduce) {
  .str__btn { transition: none; }
}

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

.stage {
  box-sizing: border-box;
  min-height: 100vh;
  display: grid;
  place-items: center;
  margin: 0;
  background: #ffd23f;
  font-family: -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  padding: clamp(8px, 4vw, 24px);
}

.str {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 12px 20px;
  border-radius: 999px;
  background: #17141a;
}

.str__dot {
  width: 8px;
  height: 8px;
  border-radius: 999px;
  background: #4cd4a6;
  flex: 0 0 auto;
}

.str__label {
  font: 600 14px/1 -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  color: #fff7e6;
  min-width: 128px;
}

.str__btn {
  margin-left: 8px;
  border: 0;
  border-radius: 12px;
  padding: 4px 12px;
  background: #fff7e6;
  color: #17141a;
  font: 700 12px/1 -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  cursor: pointer;
  transition: transform 140ms ease-out;
}
.str__btn:active {
  transform: scale(0.96);
}

@media (max-width: 340px) {
  .str {
    padding: 8px 16px;
    flex-wrap: wrap;
    justify-content: center;
  }
  .str__label {
    font-size: 12px;
    min-width: 96px;
  }
}
@media (prefers-reduced-motion: reduce) {
  .str__btn {
    transition: none;
  }
}

(function () {
  var root = document.getElementById('str');
  var btn = document.getElementById('strBtn');
  var dot = document.getElementById('strDot');
  var label = document.getElementById('strLabel');

  // 상수: 데모 안에서 "1초"를 표현하는 실제 ms(가속) · 분으로 넘어가는 기준 초 · 리셋되는 기준 초
  var DEMO_SEC_MS = 90;
  var MIN_THRESHOLD_SEC = 60;
  var RESET_AFTER_SEC = 150;

  var reduce = window.matchMedia('(prefers-reduced-motion: reduce)').matches;
  var savedAt = performance.now();

  // 계산 겹: 경과 초 = (지금 − 저장시각)÷가속ms, 초·분 환산으로 문구를 만들고 신선도(투명도)는 1 − min(1, 경과÷기준)
  function raf(ts) {
    var elapsedSec = Math.floor((ts - savedAt) / DEMO_SEC_MS);
    if (elapsedSec >= RESET_AFTER_SEC) { savedAt = ts; elapsedSec = 0; }
    var phrase;
    if (elapsedSec < 5) phrase = 'たった今保存';
    else if (elapsedSec < MIN_THRESHOLD_SEC) phrase = elapsedSec + '秒前に保存';
    else phrase = Math.floor(elapsedSec / 60) + '分前に保存';
    label.textContent = phrase;
    var fresh = 1 - Math.min(1, elapsedSec / RESET_AFTER_SEC);
    dot.style.opacity = reduce ? '1' : (0.35 + 0.65 * fresh).toFixed(3);
    requestAnimationFrame(raf);
  }
  requestAnimationFrame(raf);

  btn.addEventListener('click', function () {
    root.classList.remove('is-demo');
    savedAt = performance.now();
    label.textContent = 'たった今保存';
    dot.style.opacity = '1';
  });
})();

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

type Box<T> = { current: T };

export default function SaveStatusTimestampRelative() {
  const rootRef = useRef(null) as unknown as Box<HTMLDivElement | null>;

  useEffect(() => {
    const root = rootRef.current;
    if (!root) return;
    const dot = root.querySelector(`.${styles.dot}`) as HTMLElement | null;
    const label = root.querySelector(`.${styles.label}`) as HTMLElement | null;
    const btn = root.querySelector(`.${styles.btn}`) as HTMLElement | null;
    if (!dot || !label || !btn) return;

    // 상수: 데모 안에서 "1초"를 표현하는 실제 ms(가속) · 분으로 넘어가는 기준 초 · 리셋되는 기준 초
    const DEMO_SEC_MS = 90;
    const MIN_THRESHOLD_SEC = 60;
    const RESET_AFTER_SEC = 150;

    const reduce = window.matchMedia("(prefers-reduced-motion: reduce)").matches;
    let savedAt = performance.now();
    let rafId = 0;

    // 계산 겹: 경과 초 = (지금 − 저장시각)÷가속ms, 초·분 환산으로 문구를 만들고 신선도(투명도)는 1 − min(1, 경과÷기준)
    function raf(ts: number) {
      let elapsedSec = Math.floor((ts - savedAt) / DEMO_SEC_MS);
      if (elapsedSec >= RESET_AFTER_SEC) { savedAt = ts; elapsedSec = 0; }
      let phrase: string;
      if (elapsedSec < 5) phrase = "방금 저장됨";
      else if (elapsedSec < MIN_THRESHOLD_SEC) phrase = elapsedSec + "초 전 저장됨";
      else phrase = Math.floor(elapsedSec / 60) + "분 전 저장됨";
      label!.textContent = phrase;
      const fresh = 1 - Math.min(1, elapsedSec / RESET_AFTER_SEC);
      dot!.style.opacity = reduce ? "1" : (0.35 + 0.65 * fresh).toFixed(3);
      rafId = requestAnimationFrame(raf);
    }
    rafId = requestAnimationFrame(raf);

    function onClick() {
      root!.classList.remove(styles["is-demo"]);
      savedAt = performance.now();
      label!.textContent = "방금 저장됨";
      dot!.style.opacity = "1";
    }
    btn.addEventListener("click", onClick);

    return () => {
      cancelAnimationFrame(rafId);
      btn.removeEventListener("click", onClick);
    };
  }, []);

  return (
    <div ref={rootRef} className={`${styles.stage} ${styles.str} ${styles["is-demo"]}`}>
      <span className={styles.dot} />
      <span className={styles.label}>방금 저장됨</span>
      <button className={styles.btn} type="button">지금 저장</button>
    </div>
  );
}