02Saved-flag flash — the completion value flips to one the instant a save finishes, then falls back to zero and disappears

<main class="stage">
<div class="ssc is-demo" id="ssc">
  <div class="ssc__badge" id="sscBadge">
    <svg class="ssc__ring" viewBox="0 0 40 40" width="40" height="40">
      <circle class="ssc__circle" cx="20" cy="20" r="17"></circle>
      <polyline class="ssc__check" id="sscCheck" points="12,21 17,26 28,13"></polyline>
    </svg>
  </div>
  <span class="ssc__label" id="sscLabel">Save complete</span>
  <button class="ssc__btn" id="sscBtn" type="button">Save changes</button>
</div>
</main>

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

// 계산 겹: SVG 경로 실측 길이(getTotalLength) 기준 stroke-dashoffset 산술로 체크를 그린다 — index.html 참조
@include stage($stage-paper);

.ssc {
  display: grid;
  justify-items: center;
  gap: $sp-3;
}

.ssc__badge {
  width: 56px;
  height: 56px;
  display: grid;
  place-items: center;
  opacity: 0;
  transform: scale(.7);
  transition: opacity $dur-quick $ease-out, transform $dur-quick $ease-pop;
}

.ssc__badge--show {
  opacity: 1;
  transform: scale(1);
}

.ssc__circle {
  fill: $subject-mint;
  opacity: .16;
}

.ssc__check {
  fill: none;
  stroke: $subject-mint;
  stroke-width: 3.4;
  stroke-linecap: round;
  stroke-linejoin: round;
}

.ssc__label {
  font: 600 13px/1 -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  color: rgba($stage-ink, .64);
}

.ssc__btn {
  border: 0;
  border-radius: $r-control;
  padding: $sp-2 $sp-4;
  background: $stage-ink;
  color: $subject-cream;
  font: 700 13px/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) {
  .ssc__badge { width: 44px; height: 44px; }
}

@media (prefers-reduced-motion: reduce) {
  .ssc__badge { transition: none; }
  .ssc__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: #ffffff;
  font-family: -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  padding: clamp(8px, 4vw, 24px);
}

.ssc {
  display: grid;
  justify-items: center;
  gap: 12px;
}

.ssc__badge {
  width: 56px;
  height: 56px;
  display: grid;
  place-items: center;
  opacity: 0;
  transform: scale(0.7);
  transition: opacity 220ms ease-out, transform 220ms cubic-bezier(0.2, 1.4, 0.4, 1);
}

.ssc__badge--show {
  opacity: 1;
  transform: scale(1);
}

.ssc__circle {
  fill: #4cd4a6;
  opacity: 0.16;
}

.ssc__check {
  fill: none;
  stroke: #4cd4a6;
  stroke-width: 3.4;
  stroke-linecap: round;
  stroke-linejoin: round;
}

.ssc__label {
  font: 600 13px/1 -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  color: rgba(23, 20, 26, 0.64);
}

.ssc__btn {
  border: 0;
  border-radius: 12px;
  padding: 8px 16px;
  background: #17141a;
  color: #fff7e6;
  font: 700 13px/1 -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  cursor: pointer;
  transition: transform 140ms ease-out;
}
.ssc__btn:active {
  transform: scale(0.96);
}

@media (max-width: 340px) {
  .ssc__badge {
    width: 44px;
    height: 44px;
  }
}
@media (prefers-reduced-motion: reduce) {
  .ssc__badge {
    transition: none;
  }
  .ssc__btn {
    transition: none;
  }
}

(function () {
  var root = document.getElementById('ssc');
  var btn = document.getElementById('sscBtn');
  var badge = document.getElementById('sscBadge');
  var check = document.getElementById('sscCheck');

  // 상수: 체크 선이 그려지는 시간 · 다 그려진 뒤 머무는 시간 · 사라지는 시간 · 다음 저장까지 간격
  var DRAW_MS = 300;
  var HOLD_MS = 380;
  var FADE_MS = 200;
  var GAP_MS = 260;

  var reduce = window.matchMedia('(prefers-reduced-motion: reduce)').matches;
  // 계산 겹: getTotalLength() 로 실제 경로 길이를 재고, stroke-dashoffset = 길이×(1−t) 로 그려 나간다
  var len = check.getTotalLength();
  check.style.strokeDasharray = String(len);
  check.style.strokeDashoffset = String(len);

  var timer = null;

  function draw(cb) {
    if (reduce) { check.style.strokeDashoffset = '0'; cb(); return; }
    var start = null;
    function frame(ts) {
      if (start === null) start = ts;
      var t = Math.min(1, (ts - start) / DRAW_MS);
      check.style.strokeDashoffset = (len * (1 - t)).toFixed(2);
      if (t < 1) requestAnimationFrame(frame); else cb();
    }
    requestAnimationFrame(frame);
  }

  function cycle() {
    badge.classList.add('ssc__badge--show');
    draw(function () {
      timer = setTimeout(function () {
        badge.classList.remove('ssc__badge--show');
        timer = setTimeout(function () {
          check.style.strokeDashoffset = String(len);
          timer = setTimeout(cycle, GAP_MS);
        }, reduce ? 0 : FADE_MS);
      }, HOLD_MS);
    });
  }
  cycle();

  btn.addEventListener('click', function () {
    root.classList.remove('is-demo');
    if (timer) clearTimeout(timer);
    check.style.strokeDashoffset = String(len);
    badge.classList.remove('ssc__badge--show');
    requestAnimationFrame(cycle);
  });
})();

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

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

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

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

    // 상수: 체크 선이 그려지는 시간 · 다 그려진 뒤 머무는 시간 · 사라지는 시간 · 다음 저장까지 간격
    const DRAW_MS = 300;
    const HOLD_MS = 380;
    const FADE_MS = 200;
    const GAP_MS = 260;

    const reduce = window.matchMedia("(prefers-reduced-motion: reduce)").matches;
    // 계산 겹: getTotalLength() 로 실제 경로 길이를 재고, stroke-dashoffset = 길이×(1−t) 로 그려 나간다
    const len = check.getTotalLength();
    check.style.strokeDasharray = String(len);
    check.style.strokeDashoffset = String(len);

    let timer = 0;
    let rafId = 0;
    let stopped = false;

    function draw(cb: () => void) {
      if (reduce) { check!.style.strokeDashoffset = "0"; cb(); return; }
      let start: number | null = null;
      function frame(ts: number) {
        if (start === null) start = ts;
        const t = Math.min(1, (ts - start) / DRAW_MS);
        check!.style.strokeDashoffset = (len * (1 - t)).toFixed(2);
        if (t < 1) rafId = requestAnimationFrame(frame); else cb();
      }
      rafId = requestAnimationFrame(frame);
    }

    function cycle() {
      if (stopped) return;
      badge!.classList.add(styles["badge--show"]);
      draw(() => {
        timer = window.setTimeout(() => {
          badge!.classList.remove(styles["badge--show"]);
          timer = window.setTimeout(() => {
            check!.style.strokeDashoffset = String(len);
            timer = window.setTimeout(cycle, GAP_MS);
          }, reduce ? 0 : FADE_MS);
        }, HOLD_MS);
      });
    }
    cycle();

    function onClick() {
      root!.classList.remove(styles["is-demo"]);
      window.clearTimeout(timer);
      check!.style.strokeDashoffset = String(len);
      badge!.classList.remove(styles["badge--show"]);
      rafId = requestAnimationFrame(cycle);
    }
    btn.addEventListener("click", onClick);

    return () => {
      stopped = true;
      window.clearTimeout(timer);
      cancelAnimationFrame(rafId);
      btn.removeEventListener("click", onClick);
    };
  }, []);

  return (
    <div ref={rootRef} className={`${styles.stage} ${styles.ssc} ${styles["is-demo"]}`}>
      <div className={styles.badge}>
        <svg className={styles.ring} viewBox="0 0 40 40" width="40" height="40">
          <circle className={styles.circle} cx="20" cy="20" r="17" />
          <polyline className={styles.check} points="12,21 17,26 28,13" />
        </svg>
      </div>
      <span className={styles.label}>저장 완료</span>
      <button className={styles.btn} type="button">변경 저장</button>
    </div>
  );
}