08Reset clear spring — pressing the already-selected star again shrinks the filled value to zero with a bounced motion

<main class="stage">
<div class="sr is-demo" id="sr">
  <div class="sr__row" id="srRow">
    <button class="sr__star" type="button" data-i="1"><svg class="sr__base" viewBox="0 0 24 24"><path d="M12 .587l3.668 7.568 8.332 1.151-6.064 5.828 1.48 8.279L12 19.771l-7.416 3.642 1.48-8.279-6.064-5.828 8.332-1.151z"/></svg><span class="sr__fillclip" data-fc><svg class="sr__fill" viewBox="0 0 24 24"><path d="M12 .587l3.668 7.568 8.332 1.151-6.064 5.828 1.48 8.279L12 19.771l-7.416 3.642 1.48-8.279-6.064-5.828 8.332-1.151z"/></svg></span></button>
    <button class="sr__star" type="button" data-i="2"><svg class="sr__base" viewBox="0 0 24 24"><path d="M12 .587l3.668 7.568 8.332 1.151-6.064 5.828 1.48 8.279L12 19.771l-7.416 3.642 1.48-8.279-6.064-5.828 8.332-1.151z"/></svg><span class="sr__fillclip" data-fc><svg class="sr__fill" viewBox="0 0 24 24"><path d="M12 .587l3.668 7.568 8.332 1.151-6.064 5.828 1.48 8.279L12 19.771l-7.416 3.642 1.48-8.279-6.064-5.828 8.332-1.151z"/></svg></span></button>
    <button class="sr__star" type="button" data-i="3"><svg class="sr__base" viewBox="0 0 24 24"><path d="M12 .587l3.668 7.568 8.332 1.151-6.064 5.828 1.48 8.279L12 19.771l-7.416 3.642 1.48-8.279-6.064-5.828 8.332-1.151z"/></svg><span class="sr__fillclip" data-fc><svg class="sr__fill" viewBox="0 0 24 24"><path d="M12 .587l3.668 7.568 8.332 1.151-6.064 5.828 1.48 8.279L12 19.771l-7.416 3.642 1.48-8.279-6.064-5.828 8.332-1.151z"/></svg></span></button>
    <button class="sr__star" type="button" data-i="4"><svg class="sr__base" viewBox="0 0 24 24"><path d="M12 .587l3.668 7.568 8.332 1.151-6.064 5.828 1.48 8.279L12 19.771l-7.416 3.642 1.48-8.279-6.064-5.828 8.332-1.151z"/></svg><span class="sr__fillclip" data-fc><svg class="sr__fill" viewBox="0 0 24 24"><path d="M12 .587l3.668 7.568 8.332 1.151-6.064 5.828 1.48 8.279L12 19.771l-7.416 3.642 1.48-8.279-6.064-5.828 8.332-1.151z"/></svg></span></button>
    <button class="sr__star" type="button" data-i="5"><svg class="sr__base" viewBox="0 0 24 24"><path d="M12 .587l3.668 7.568 8.332 1.151-6.064 5.828 1.48 8.279L12 19.771l-7.416 3.642 1.48-8.279-6.064-5.828 8.332-1.151z"/></svg><span class="sr__fillclip" data-fc><svg class="sr__fill" viewBox="0 0 24 24"><path d="M12 .587l3.668 7.568 8.332 1.151-6.064 5.828 1.48 8.279L12 19.771l-7.416 3.642 1.48-8.279-6.064-5.828 8.332-1.151z"/></svg></span></button>
  </div>
  <div class="sr__readout"><span id="srHint">Click the same star again → reset</span></div>
</div>
</main>

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

// 계산 겹: 초기화 순간 이미 채워져 있던 별에만 스프링 이징($ease-elastic, 목표를 넘겼다가
// 되돌아오는 오버슛 곡선)으로 팝 애니메이션을 걸어 "튕기며 사라지는" 느낌을 만든다.
@include stage($stage-paper);

.sr {
  display: grid;
  gap: $sp-5;
  place-items: center;
}

.sr__row { display: flex; gap: $sp-2; }

.sr__star {
  position: relative;
  width: 44px;
  height: 44px;
  padding: 0;
  border: 0;
  background: none;
  cursor: pointer;

  &--bounce { animation: srBounce $dur-enter $ease-elastic; }
}

.sr__base,
.sr__fill svg {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
}

.sr__base { fill: $subject-ink; opacity: .18; }

.sr__fillclip {
  position: absolute;
  inset: 0;
  width: 0%;
  overflow: hidden;
  transition: width $dur-base $ease-out;
}

.sr__fill { fill: $subject-blue-deep; }

.sr__readout {
  font: 500 13px/1.3 -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  color: $subject-ink;
  opacity: .7;
}

@keyframes srBounce {
  0%   { transform: scale(1); }
  35%  { transform: scale(1.3); }
  100% { transform: scale(.85); opacity: 0; }
}

@media (max-width: 340px) {
  .sr__star { width: 34px; height: 34px; }
  .sr__row { gap: $sp-1; }
  .sr__readout { font-size: 11px; }
}

@media (prefers-reduced-motion: reduce) {
  .sr__fillclip { transition: none; }
  .sr__star--bounce { animation: 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);
}

.sr {
  display: grid;
  gap: 20px;
  place-items: center;
}

.sr__row {
  display: flex;
  gap: 8px;
}

.sr__star {
  position: relative;
  width: 44px;
  height: 44px;
  padding: 0;
  border: 0;
  background: none;
  cursor: pointer;
}
.sr__star--bounce {
  animation: srBounce 600ms cubic-bezier(0.34, 1.56, 0.64, 1);
}

.sr__base,
.sr__fill svg {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
}

.sr__base {
  fill: #17141a;
  opacity: 0.18;
}

.sr__fillclip {
  position: absolute;
  inset: 0;
  width: 0%;
  overflow: hidden;
  transition: width 300ms ease-out;
}

.sr__fill {
  fill: #0a4fe8;
}

.sr__readout {
  font: 500 13px/1.3 -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  color: #17141a;
  opacity: 0.7;
}

@keyframes srBounce {
  0% {
    transform: scale(1);
  }
  35% {
    transform: scale(1.3);
  }
  100% {
    transform: scale(0.85);
    opacity: 0;
  }
}
@media (max-width: 340px) {
  .sr__star {
    width: 34px;
    height: 34px;
  }
  .sr__row {
    gap: 4px;
  }
  .sr__readout {
    font-size: 11px;
  }
}
@media (prefers-reduced-motion: reduce) {
  .sr__fillclip {
    transition: none;
  }
  .sr__star--bounce {
    animation: none;
  }
}

(function () {
  var root = document.getElementById('sr');
  var stars = Array.prototype.slice.call(document.querySelectorAll('.sr__star'));
  var value = 4;

  function paint(v) {
    stars.forEach(function (s, idx) {
      var starVal = Math.max(0, Math.min(1, v - idx));
      s.querySelector('[data-fc]').style.width = (starVal * 100).toFixed(1) + '%';
    });
  }

  // 계산 겹: 초기화가 일어나면 채움 값을 0으로 보내는 동시에, 이미 채워졌던 별에만
  // 스프링 이징(퇴장 전 오버슛)이 걸린 팝 애니메이션 클래스를 씌운다.
  function reset() {
    var wasFilled = stars.filter(function (s, idx) { return idx < value; });
    value = 0;
    paint(value);
    wasFilled.forEach(function (s) { s.classList.add('sr__star--bounce'); });
    setTimeout(function () {
      wasFilled.forEach(function (s) { s.classList.remove('sr__star--bounce'); });
    }, 620);
  }

  stars.forEach(function (s) {
    var i = Number(s.getAttribute('data-i'));
    s.addEventListener('click', function () {
      root.classList.remove('is-demo'); stopAutoplay();
      if (i === value) reset(); else { value = i; paint(value); }
    });
  });

  paint(value);

  // 자동 루프: 값을 채운 뒤 같은 별을 다시 누른 상태를 흉내내 스프링 초기화를 반복해 보여준다.
  var phase = 0;
  var autoTimer = null;
  function autoTick() {
    if (phase === 0) { value = 4; paint(value); }
    else if (phase === 1) { reset(); }
    phase = (phase + 1) % 3;
  }
  var reduce = window.matchMedia('(prefers-reduced-motion: reduce)').matches;
  function stopAutoplay() { if (autoTimer) { clearInterval(autoTimer); autoTimer = null; } }
  if (!reduce) { autoTimer = setInterval(autoTick, 700); autoTick(); }
})();

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

const STAR_PATH =
  "M12 .587l3.668 7.568 8.332 1.151-6.064 5.828 1.48 8.279L12 19.771l-7.416 3.642 1.48-8.279-6.064-5.828 8.332-1.151z";

export default function ResetClearSpring() {
  const rootRef = useRef<HTMLDivElement | null>(null);

  useEffect(() => {
    const root = rootRef.current;
    if (!root) return;
    const stars = Array.prototype.slice.call(
      root.querySelectorAll(`.${styles.star}`)
    ) as HTMLElement[];
    let value = 4;

    function paint(v: number) {
      stars.forEach((s, idx) => {
        const starVal = Math.max(0, Math.min(1, v - idx));
        s.querySelector<HTMLElement>(`.${styles.fillclip}`)!.style.width = (starVal * 100).toFixed(1) + "%";
      });
    }

    // 계산 겹: 초기화가 일어나면 채움 값을 0으로 보내는 동시에, 이미 채워졌던 별에만
    // 스프링 이징(퇴장 전 오버슛)이 걸린 팝 애니메이션 클래스를 씌운다.
    function reset() {
      const wasFilled = stars.filter((_s, idx) => idx < value);
      value = 0;
      paint(value);
      wasFilled.forEach((s) => s.classList.add(styles.bounce));
      window.setTimeout(() => {
        wasFilled.forEach((s) => s.classList.remove(styles.bounce));
      }, 620);
    }

    const clickHandlers: Array<() => void> = [];
    stars.forEach((s, idx) => {
      const i = idx + 1;
      const handler = () => {
        stopAutoplay();
        if (i === value) reset(); else { value = i; paint(value); }
      };
      clickHandlers.push(handler);
      s.addEventListener("click", handler);
    });

    paint(value);

    // 자동 루프: 값을 채운 뒤 같은 별을 다시 누른 상태를 흉내내 스프링 초기화를 반복해 보여준다.
    let phase = 0;
    let autoTimer: number | null = null;
    function autoTick() {
      if (phase === 0) { value = 4; paint(value); }
      else if (phase === 1) { reset(); }
      phase = (phase + 1) % 3;
    }
    function stopAutoplay() { if (autoTimer !== null) { window.clearInterval(autoTimer); autoTimer = null; } }
    const reduce = window.matchMedia("(prefers-reduced-motion: reduce)").matches;
    if (!reduce) { autoTimer = window.setInterval(autoTick, 700); autoTick(); }

    return () => {
      stopAutoplay();
      stars.forEach((s, idx) => s.removeEventListener("click", clickHandlers[idx]));
    };
  }, []);

  return (
    <div ref={rootRef} className={styles.stage}>
      <div className={styles.sr}>
        <div className={styles.row}>
          {[1, 2, 3, 4, 5].map((i) => (
            <button key={i} type="button" className={styles.star}>
              <svg className={styles.base} viewBox="0 0 24 24"><path d={STAR_PATH} /></svg>
              <span className={styles.fillclip}>
                <svg className={styles.fill} viewBox="0 0 24 24"><path d={STAR_PATH} /></svg>
              </span>
            </button>
          ))}
        </div>
        <div className={styles.readout}>같은 별 다시 클릭 → 초기화</div>
      </div>
    </div>
  );
}