05Rubber-band drag close — a drag distance value that meets growing resistance past a threshold

<main class="stage">
<div class="cswr is-demo" id="cswr">
  <ul class="cswr__list">
    <li class="cswr__row" id="cswrRow">
      <span class="cswr__trash" aria-hidden="true">
        <svg viewBox="0 0 256 256" width="18" height="18"><g fill="currentColor"><path d="M216 48h-40v-8a24 24 0 0 0-24-24h-48a24 24 0 0 0-24 24v8H40a8 8 0 0 0 0 16h8v144a16 16 0 0 0 16 16h128a16 16 0 0 0 16-16V64h8a8 8 0 0 0 0-16ZM96 40a8 8 0 0 1 8-8h48a8 8 0 0 1 8 8v8H96Zm96 168H64V64h128Zm-80-104v64a8 8 0 0 1-16 0v-64a8 8 0 0 1 16 0Zm48 0v64a8 8 0 0 1-16 0v-64a8 8 0 0 1 16 0Z"/></g></svg>
      </span>
      <span class="cswr__card" id="cswrCard">
        <span class="cswr__name">Running Shoes</span>
        <span class="cswr__price">$41</span>
      </span>
    </li>
  </ul>
</div>
</main>

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

// 계산 겹: 드래그 거리가 임계값(THRESHOLD)을 넘으면 저항 함수 rubberband() 가 지수 감쇠로
// 이동량을 압축한다(index.html) — 당길수록 화면 반영 비율이 줄어드는 고무줄 공식.

$duration: $dur-quick;
$easing: $ease-out;
$color: $error;

@include stage($stage-ink);

.stage { position: relative; overflow: hidden; }

.cswr {
  width: min(330px, 84vw);
}

.cswr__list {
  list-style: none;
  margin: 0;
  padding: 0;
}

.cswr__row {
  position: relative;
  border-radius: $r-control;
  overflow: hidden;
  --trash-opacity: 0;
}

.cswr__trash {
  position: absolute;
  inset: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  background: $color;
  color: $subject-cream;
  opacity: var(--trash-opacity);
}

.cswr__card {
  position: relative;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: $sp-5;
  border-radius: $r-control;
  background: $subject-cream;
  touch-action: none;
  cursor: grab;
  will-change: transform;
}

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

.cswr__price {
  color: $subject-ink;
  font-weight: 600;
  font-size: 13px;
}

@media (max-width: 340px) {
  .cswr { width: min(220px, 70vw); }
  .cswr__card { padding: $sp-3; }
}

@media (prefers-reduced-motion: reduce) {
  .cswr__card { 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;
  overflow: hidden;
}

.cswr {
  width: min(330px, 84vw);
}

.cswr__list {
  list-style: none;
  margin: 0;
  padding: 0;
}

.cswr__row {
  position: relative;
  border-radius: 12px;
  overflow: hidden;
  --trash-opacity: 0;
}

.cswr__trash {
  position: absolute;
  inset: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  background: #c2361a;
  color: #fff7e6;
  opacity: var(--trash-opacity);
}

.cswr__card {
  position: relative;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 20px;
  border-radius: 12px;
  background: #fff7e6;
  touch-action: none;
  cursor: grab;
  will-change: transform;
}

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

.cswr__price {
  color: #17141a;
  font-weight: 600;
  font-size: 13px;
}

@media (max-width: 340px) {
  .cswr {
    width: min(220px, 70vw);
  }
  .cswr__card {
    padding: 12px;
  }
}
@media (prefers-reduced-motion: reduce) {
  .cswr__card {
    transition: none !important;
  }
}

(function () {
  var root = document.getElementById('cswr');
  var card = document.getElementById('cswrCard');
  var row = document.getElementById('cswrRow');

  // 계산 겹: 드래그 거리가 임계값을 넘으면 저항 함수(rubberband())로 이동량을 압축한다 —
  // 당길수록 화면에 반영되는 비율이 줄어드는 진짜 고무줄 공식(iOS 오버스크롤과 같은 계열),
  // 단순 clamp 가 아니다.
  var THRESHOLD = 90;
  var MAX_PULL = 140;
  function rubberband(dx) {
    var sign = dx < 0 ? -1 : 1;
    var abs = Math.abs(dx);
    if (abs <= THRESHOLD) { return dx; }
    var over = abs - THRESHOLD;
    var compressed = MAX_PULL * (1 - Math.exp(-over / MAX_PULL));
    return sign * (THRESHOLD + compressed);
  }

  var dragging = false;
  var startX = 0;
  var current = 0;

  function apply(dx) {
    var x = rubberband(dx);
    card.style.transform = 'translateX(' + x.toFixed(2) + 'px)';
    var trashOpacity = Math.min(1, Math.abs(x) / THRESHOLD);
    row.style.setProperty('--trash-opacity', trashOpacity.toFixed(3));
  }

  function onDown(clientX) {
    dragging = true;
    startX = clientX - current;
    root.classList.remove('is-demo');
    stopAutoplay();
  }
  function onMove(clientX) {
    if (!dragging) { return; }
    current = clientX - startX;
    apply(current);
  }
  function onUp() {
    if (!dragging) { return; }
    dragging = false;
    if (Math.abs(current) > THRESHOLD * 1.3) {
      dismiss(current < 0 ? -1 : 1);
    } else {
      current = 0;
      card.style.transition = 'transform ' + DUR + 'ms';
      apply(0);
      setTimeout(function () { card.style.transition = ''; }, DUR);
    }
  }
  var DUR = 260;

  function dismiss(dir) {
    card.style.transition = 'transform 320ms ease-in, opacity 320ms ease-in';
    card.style.transform = 'translateX(' + (dir * 420) + 'px)';
    card.style.opacity = '0';
    setTimeout(function () {
      card.style.transition = '';
      card.style.transform = 'translateX(0)';
      card.style.opacity = '1';
      current = 0;
      row.style.setProperty('--trash-opacity', '0');
    }, 420);
  }

  card.addEventListener('pointerdown', function (e) { onDown(e.clientX); });
  window.addEventListener('pointermove', function (e) { onMove(e.clientX); });
  window.addEventListener('pointerup', onUp);

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

  function autoStep() {
    var t0 = performance.now();
    var DUR_MS = 900;
    function anim(now) {
      var p = Math.min(1, (now - t0) / DUR_MS);
      var dx = p < 0.7 ? (p / 0.7) * 270 : 270 * (1 - (p - 0.7) / 0.3);
      apply(dx);
      if (p < 1) { requestAnimationFrame(anim); } else { apply(0); }
    }
    requestAnimationFrame(anim);
  }

  var reduce = window.matchMedia('(prefers-reduced-motion: reduce)').matches;
  if (!reduce) {
    autoStep();
    autoplayTimer = setInterval(autoStep, 1500);
  }
})();

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

export type CartDrawerSwipeDismissRubberbandProps = {
  duration?: number;
  color?: string;
};

// 계산 겹: 드래그 거리가 임계값을 넘으면 저항 함수(rubberband())로 이동량을 압축한다 —
// 당길수록 화면에 반영되는 비율이 줄어드는 진짜 고무줄 공식(iOS 오버스크롤과 같은 계열),
// 단순 clamp 가 아니다.
const THRESHOLD = 90;
const MAX_PULL = 140;
function rubberband(dx: number): number {
  const sign = dx < 0 ? -1 : 1;
  const abs = Math.abs(dx);
  if (abs <= THRESHOLD) return dx;
  const over = abs - THRESHOLD;
  const compressed = MAX_PULL * (1 - Math.exp(-over / MAX_PULL));
  return sign * (THRESHOLD + compressed);
}

const DUR = 260;

export default function CartDrawerSwipeDismissRubberband({
  color = "#c2361a",
}: CartDrawerSwipeDismissRubberbandProps) {
  const rootRef = useRef<HTMLDivElement | null>(null);
  const cardRef = useRef<HTMLSpanElement | null>(null);
  const rowRef = useRef<HTMLLIElement | null>(null);
  const draggingRef = useRef(false);
  const startXRef = useRef(0);
  const currentRef = useRef(0);
  const timerRef = useRef<ReturnType<typeof setInterval> | null>(null);

  useEffect(() => {
    function apply(dx: number) {
      const card = cardRef.current;
      const row = rowRef.current;
      if (!card || !row) return;
      const x = rubberband(dx);
      card.style.transform = `translateX(${x.toFixed(2)}px)`;
      const trashOpacity = Math.min(1, Math.abs(x) / THRESHOLD);
      row.style.setProperty("--trash-opacity", trashOpacity.toFixed(3));
    }

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

    function dismiss(dir: number) {
      const card = cardRef.current;
      const row = rowRef.current;
      if (!card || !row) return;
      card.style.transition = "transform 320ms ease-in, opacity 320ms ease-in";
      card.style.transform = `translateX(${dir * 420}px)`;
      card.style.opacity = "0";
      setTimeout(() => {
        card.style.transition = "";
        card.style.transform = "translateX(0)";
        card.style.opacity = "1";
        currentRef.current = 0;
        row.style.setProperty("--trash-opacity", "0");
      }, 420);
    }

    function onDown(clientX: number) {
      draggingRef.current = true;
      startXRef.current = clientX - (currentRef.current ?? 0);
      rootRef.current?.classList.remove(styles.isDemo);
      stopAutoplay();
    }
    function onMove(clientX: number) {
      if (!draggingRef.current) return;
      currentRef.current = clientX - (startXRef.current ?? 0);
      apply(currentRef.current ?? 0);
    }
    function onUp() {
      if (!draggingRef.current) return;
      draggingRef.current = false;
      const card = cardRef.current;
      const cur = currentRef.current ?? 0;
      if (Math.abs(cur) > THRESHOLD * 1.3) {
        dismiss(cur < 0 ? -1 : 1);
      } else {
        currentRef.current = 0;
        if (card) {
          card.style.transition = `transform ${DUR}ms`;
          apply(0);
          setTimeout(() => {
            card.style.transition = "";
          }, DUR);
        }
      }
    }

    const onPointerDown = (e: PointerEvent) => onDown(e.clientX);
    const onPointerMove = (e: PointerEvent) => onMove(e.clientX);
    cardRef.current?.addEventListener("pointerdown", onPointerDown);
    window.addEventListener("pointermove", onPointerMove);
    window.addEventListener("pointerup", onUp);

    function autoStep() {
      const t0 = performance.now();
      const DUR_MS = 900;
      function anim(now: number) {
        const p = Math.min(1, (now - t0) / DUR_MS);
        const dx = p < 0.7 ? (p / 0.7) * 270 : 270 * (1 - (p - 0.7) / 0.3);
        apply(dx);
        if (p < 1) {
          requestAnimationFrame(anim);
        } else {
          apply(0);
        }
      }
      requestAnimationFrame(anim);
    }

    const reduce = window.matchMedia("(prefers-reduced-motion: reduce)").matches;
    if (!reduce) {
      autoStep();
      timerRef.current = setInterval(autoStep, 1500);
    }

    return () => {
      stopAutoplay();
      cardRef.current?.removeEventListener("pointerdown", onPointerDown);
      window.removeEventListener("pointermove", onPointerMove);
      window.removeEventListener("pointerup", onUp);
    };
  }, []);

  return (
    <div ref={rootRef} className={`${styles.stage} ${styles.isDemo}`} style={{ "--color": color } as CSSProperties}>
      <ul className={styles.list}>
        <li ref={rowRef} className={styles.row}>
          <span className={styles.trash} aria-hidden="true">
            <svg viewBox="0 0 256 256" width="18" height="18"><g fill="currentColor"><path d="M216 48h-40v-8a24 24 0 0 0-24-24h-48a24 24 0 0 0-24 24v8H40a8 8 0 0 0 0 16h8v144a16 16 0 0 0 16 16h128a16 16 0 0 0 16-16V64h8a8 8 0 0 0 0-16ZM96 40a8 8 0 0 1 8-8h48a8 8 0 0 1 8 8v8H96Zm96 168H64V64h128Zm-80-104v64a8 8 0 0 1-16 0v-64a8 8 0 0 1 16 0Zm48 0v64a8 8 0 0 1-16 0v-64a8 8 0 0 1 16 0Z"/></g></svg>
          </span>
          <span ref={cardRef} className={styles.card}>
            <span className={styles.name}>런닝화</span>
            <span className={styles.price}>$41</span>
          </span>
        </li>
      </ul>
    </div>
  );
}