01Slide overshoot — a cart panel whose open position value passes its target before settling back

<main class="stage">
<div class="cdso is-demo" id="cdso">
  <div class="cdso__page">
    <div class="cdso__card"></div>
    <div class="cdso__card"></div>
    <div class="cdso__card"></div>
    <button class="cdso__toggle" id="cdsoToggle" type="button">Open cart</button>
  </div>
  <div class="cdso__backdrop" id="cdsoBackdrop"></div>
  <aside class="cdso__panel" id="cdsoPanel">
    <header class="cdso__head">
      <span class="cdso__title">Cart</span>
      <button class="cdso__close" id="cdsoClose" type="button" aria-label="Close">
        <svg viewBox="0 0 256 256" width="16" height="16" aria-hidden="true"><g fill="currentColor"><path d="M205.66 194.34a8 8 0 0 1-11.32 11.32L128 139.31l-66.34 66.35a8 8 0 0 1-11.32-11.32L116.69 128L50.34 61.66a8 8 0 0 1 11.32-11.32L128 116.69l66.34-66.35a8 8 0 0 1 11.32 11.32L139.31 128Z"/></g></svg>
      </button>
    </header>
    <ul class="cdso__list">
      <li class="cdso__row"><span>Cotton Tee</span><b>$24</b></li>
      <li class="cdso__row"><span>Canvas Tote</span><b>$18</b></li>
      <li class="cdso__row"><span>Ceramic Mug</span><b>$12</b></li>
    </ul>
    <footer class="cdso__foot"><span>Total</span><b>$54</b></footer>
  </aside>
</div>
</main>

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

// 계산 겹: JS 가 감쇠 조화진동자 방정식(springProgress())으로 위치 값을 매 프레임 직접 계산해
// translateX 에 대입한다 — CSS 는 결과를 받기만 하고 @keyframes 로 흉내내지 않는다.

$duration: $dur-enter;
$easing: $ease-spring;
$color: $subject-cream;

@include stage($stage-ink);

.stage { position: relative; }

.cdso__page {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: $sp-3;
  width: min(200px, 62vw);
}

.cdso__card {
  width: 100%;
  height: 40px;
  border-radius: $r-control;
  background: rgba(255, 247, 230, .12);
}

.cdso__toggle {
  margin-top: $sp-2;
  border: 0;
  border-radius: $r-pill;
  padding: $sp-2 $sp-5;
  background: $color;
  color: $subject-ink;
  font-family: inherit;
  font-weight: 700;
  font-size: 12px;
  cursor: pointer;
}

.cdso__backdrop {
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, .55);
  opacity: 0;
  pointer-events: none;
}

.cdso__panel {
  position: fixed;
  top: 0;
  right: 0;
  bottom: 0;
  width: min(72%, 240px);
  box-sizing: border-box;
  display: flex;
  flex-direction: column;
  background: $subject-cream;
  padding: $sp-4;
  gap: $sp-3;
  transform: translateX(100%);
  box-shadow: $shadow-raised;
}

.cdso__head {
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.cdso__title {
  color: $subject-ink;
  font-weight: 700;
  font-size: 14px;
}

.cdso__close {
  width: 28px;
  height: 28px;
  border: 0;
  border-radius: $r-pill;
  background: rgba(23, 20, 26, .08);
  color: $subject-ink;
  display: grid;
  place-items: center;
  cursor: pointer;
}

.cdso__list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  flex-direction: column;
  gap: $sp-2;
}

.cdso__row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: $sp-2 $sp-3;
  border-radius: $r-sm;
  background: rgba(23, 20, 26, .06);
  color: $subject-ink;
  font-size: 12px;
  font-weight: 600;
}

.cdso__foot {
  margin-top: auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding-top: $sp-3;
  border-top: 1px solid rgba(23, 20, 26, .12);
  color: $subject-ink;
  font-weight: 700;
  font-size: 14px;
}

@media (max-width: 340px) {
  .cdso__page { width: min(170px, 60vw); gap: $sp-2; }
  .cdso__card { height: 32px; }
  .cdso__panel { width: min(78%, 200px); padding: $sp-3; gap: $sp-2; }
  .cdso__row { font-size: 11px; }
}

@media (prefers-reduced-motion: reduce) {
  .cdso__panel, .cdso__backdrop { transition: none !important; }
}

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

.stage {
  box-sizing: border-box;
  min-height: 100vh;
  display: grid;
  place-items: center;
  margin: 0;
  background: #17141a;
  font-family: -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  padding: clamp(8px, 4vw, 24px);
}

.stage {
  position: relative;
}

.cdso__page {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 12px;
  width: min(200px, 62vw);
}

.cdso__card {
  width: 100%;
  height: 40px;
  border-radius: 12px;
  background: rgba(255, 247, 230, 0.12);
}

.cdso__toggle {
  margin-top: 8px;
  border: 0;
  border-radius: 999px;
  padding: 8px 20px;
  background: #fff7e6;
  color: #17141a;
  font-family: inherit;
  font-weight: 700;
  font-size: 12px;
  cursor: pointer;
}

.cdso__backdrop {
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.55);
  opacity: 0;
  pointer-events: none;
}

.cdso__panel {
  position: fixed;
  top: 0;
  right: 0;
  bottom: 0;
  width: min(72%, 240px);
  box-sizing: border-box;
  display: flex;
  flex-direction: column;
  background: #fff7e6;
  padding: 16px;
  gap: 12px;
  transform: translateX(100%);
  box-shadow: 0 14px 24px rgba(23, 20, 26, 0.32);
}

.cdso__head {
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.cdso__title {
  color: #17141a;
  font-weight: 700;
  font-size: 14px;
}

.cdso__close {
  width: 28px;
  height: 28px;
  border: 0;
  border-radius: 999px;
  background: rgba(23, 20, 26, 0.08);
  color: #17141a;
  display: grid;
  place-items: center;
  cursor: pointer;
}

.cdso__list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.cdso__row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 8px 12px;
  border-radius: 8px;
  background: rgba(23, 20, 26, 0.06);
  color: #17141a;
  font-size: 12px;
  font-weight: 600;
}

.cdso__foot {
  margin-top: auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding-top: 12px;
  border-top: 1px solid rgba(23, 20, 26, 0.12);
  color: #17141a;
  font-weight: 700;
  font-size: 14px;
}

@media (max-width: 340px) {
  .cdso__page {
    width: min(170px, 60vw);
    gap: 8px;
  }
  .cdso__card {
    height: 32px;
  }
  .cdso__panel {
    width: min(78%, 200px);
    padding: 12px;
    gap: 8px;
  }
  .cdso__row {
    font-size: 11px;
  }
}
@media (prefers-reduced-motion: reduce) {
  .cdso__panel, .cdso__backdrop {
    transition: none !important;
  }
}

(function () {
  var root = document.getElementById('cdso');
  var panel = document.getElementById('cdsoPanel');
  var backdrop = document.getElementById('cdsoBackdrop');
  var toggle = document.getElementById('cdsoToggle');
  var closeBtn = document.getElementById('cdsoClose');

  // 계산 겹: 감쇠 조화진동자(스프링) 방정식을 매 프레임 직접 풀어 위치 값을 만든다 — easing 곡선을
  // 빌려 쓰는 게 아니라 감쇠비(ZETA)·고유진동수(OMEGA) 로 목표를 넘었다가(오버슛) 되돌아오는 값을 계산한다.
  var ZETA = 0.42;
  var OMEGA = 9.5;
  var OMEGA_D = OMEGA * Math.sqrt(1 - ZETA * ZETA);
  function springProgress(tSec) {
    if (tSec <= 0) { return 0; }
    var env = Math.exp(-ZETA * OMEGA * tSec);
    return 1 - env * (Math.cos(OMEGA_D * tSec) + (ZETA * OMEGA / OMEGA_D) * Math.sin(OMEGA_D * tSec));
  }

  var DURATION_S = 0.85;
  var isOpen = false;
  var raf = null;

  function apply(v) {
    var pct = (1 - v) * 100;
    panel.style.transform = 'translateX(' + pct.toFixed(2) + '%)';
    backdrop.style.opacity = Math.min(1, Math.max(0, v)).toFixed(3);
  }

  function run(closing) {
    if (raf) { cancelAnimationFrame(raf); }
    var start = performance.now();
    function frame(now) {
      var t = (now - start) / 1000;
      var raw = springProgress(Math.min(t, DURATION_S));
      var v = closing ? (1 - raw) : raw;
      apply(v);
      if (t < DURATION_S) {
        raf = requestAnimationFrame(frame);
      } else {
        apply(closing ? 0 : 1);
        raf = null;
        isOpen = !closing;
      }
    }
    raf = requestAnimationFrame(frame);
  }

  function stopAutoplay() {
    if (autoplayTimer) { clearInterval(autoplayTimer); autoplayTimer = null; }
  }

  toggle.addEventListener('click', function () {
    root.classList.remove('is-demo');
    stopAutoplay();
    run(isOpen);
  });
  closeBtn.addEventListener('click', function () {
    root.classList.remove('is-demo');
    stopAutoplay();
    run(true);
  });
  backdrop.addEventListener('click', function () {
    root.classList.remove('is-demo');
    stopAutoplay();
    run(true);
  });

  var autoplayTimer = null;
  function autoplayTick() {
    run(isOpen);
  }

  var reduce = window.matchMedia('(prefers-reduced-motion: reduce)').matches;
  if (reduce) {
    apply(1);
  } else {
    run(false);
    autoplayTimer = setInterval(autoplayTick, 1050);
  }
})();

import { useEffect, useRef } from "react";
import type { CSSProperties } from "react";
import styles from "./CartDrawerSlideSpringOvershoot.module.scss";

export type CartDrawerSlideSpringOvershootProps = {
  /** 스프링이 정착하는 데 걸리는 대략 시간 (기본 850ms) */
  duration?: number;
  color?: string;
};

// 계산 겹: 감쇠 조화진동자(스프링) 방정식을 매 프레임 직접 풀어 위치 값을 만든다 — easing 곡선을
// 빌려 쓰는 게 아니라 감쇠비(ZETA)·고유진동수(OMEGA) 로 목표를 넘었다가(오버슛) 되돌아오는 값을 계산한다.
const ZETA = 0.42;
const OMEGA = 9.5;
const OMEGA_D = OMEGA * Math.sqrt(1 - ZETA * ZETA);

function springProgress(tSec: number): number {
  if (tSec <= 0) return 0;
  const env = Math.exp(-ZETA * OMEGA * tSec);
  return 1 - env * (Math.cos(OMEGA_D * tSec) + ((ZETA * OMEGA) / OMEGA_D) * Math.sin(OMEGA_D * tSec));
}

export default function CartDrawerSlideSpringOvershoot({
  duration = 850,
  color = "#fff7e6",
}: CartDrawerSlideSpringOvershootProps) {
  const rootRef = useRef<HTMLDivElement | null>(null);
  const panelRef = useRef<HTMLElement | null>(null);
  const backdropRef = useRef<HTMLDivElement | null>(null);
  const isOpenRef = useRef(false);
  const rafRef = useRef<number | null>(null);
  const timerRef = useRef<ReturnType<typeof setInterval> | null>(null);

  useEffect(() => {
    const durationS = duration / 1000;

    function apply(v: number) {
      const panel = panelRef.current;
      const backdrop = backdropRef.current;
      if (!panel || !backdrop) return;
      const pct = (1 - v) * 100;
      panel.style.transform = `translateX(${pct.toFixed(2)}%)`;
      backdrop.style.opacity = Math.min(1, Math.max(0, v)).toFixed(3);
    }

    function run(closing: boolean) {
      if (rafRef.current) cancelAnimationFrame(rafRef.current);
      const start = performance.now();
      function frame(now: number) {
        const t = (now - start) / 1000;
        const raw = springProgress(Math.min(t, durationS));
        const v = closing ? 1 - raw : raw;
        apply(v);
        if (t < durationS) {
          rafRef.current = requestAnimationFrame(frame);
        } else {
          apply(closing ? 0 : 1);
          rafRef.current = null;
          isOpenRef.current = !closing;
        }
      }
      rafRef.current = requestAnimationFrame(frame);
    }

    function stopAutoplay() {
      if (timerRef.current) {
        clearInterval(timerRef.current);
        timerRef.current = null;
      }
    }

    function onRealInput(closing: boolean) {
      rootRef.current?.classList.remove(styles.isDemo);
      stopAutoplay();
      run(closing);
    }

    const toggle = () => onRealInput(!!isOpenRef.current);
    const close = () => onRealInput(true);

    const toggleEl = rootRef.current?.querySelector<HTMLButtonElement>(`.${styles.toggle}`);
    const closeEl = rootRef.current?.querySelector<HTMLButtonElement>(`.${styles.close}`);
    toggleEl?.addEventListener("click", toggle);
    closeEl?.addEventListener("click", close);
    backdropRef.current?.addEventListener("click", close);

    const reduce = window.matchMedia("(prefers-reduced-motion: reduce)").matches;
    if (reduce) {
      apply(1);
    } else {
      run(false);
      timerRef.current = setInterval(() => run(!!isOpenRef.current), 1050);
    }

    return () => {
      stopAutoplay();
      if (rafRef.current) cancelAnimationFrame(rafRef.current);
      toggleEl?.removeEventListener("click", toggle);
      closeEl?.removeEventListener("click", close);
      backdropRef.current?.removeEventListener("click", close);
    };
  }, [duration]);

  return (
    <div ref={rootRef} className={`${styles.stage} ${styles.isDemo}`} style={{ "--color": color } as CSSProperties}>
      <div className={styles.page}>
        <div className={styles.card} />
        <div className={styles.card} />
        <div className={styles.card} />
        <button className={styles.toggle} type="button">장바구니 열기</button>
      </div>
      <div ref={backdropRef} className={styles.backdrop} />
      <aside ref={panelRef} className={styles.panel}>
        <header className={styles.head}>
          <span className={styles.title}>장바구니</span>
          <button className={styles.close} type="button" aria-label="닫기">
            <svg viewBox="0 0 256 256" width="16" height="16" aria-hidden="true"><g fill="currentColor"><path d="M205.66 194.34a8 8 0 0 1-11.32 11.32L128 139.31l-66.34 66.35a8 8 0 0 1-11.32-11.32L116.69 128L50.34 61.66a8 8 0 0 1 11.32-11.32L128 116.69l66.34-66.35a8 8 0 0 1 11.32 11.32L139.31 128Z"/></g></svg>
          </button>
        </header>
        <ul className={styles.list}>
          <li className={styles.row}><span>코튼 티셔츠</span><b>$24</b></li>
          <li className={styles.row}><span>캔버스 백</span><b>$18</b></li>
          <li className={styles.row}><span>세라믹 머그</span><b>$12</b></li>
        </ul>
        <footer className={styles.foot}><span>합계</span><b>$54</b></footer>
      </aside>
    </div>
  );
}