07Sheet-swap value toggle — as the screen-width value narrows, a popover value changes into a bottom-sheet value that rises from below

<main class="stage">
<div class="ms is-demo" id="ms">
  <div class="ms__viewport" id="msViewport">
    <button type="button" class="ms__field" id="msField">
      <span class="ms__fieldLabel">Date</span>
      <span class="ms__fieldValue">March 14, 2026</span>
    </button>
    <div class="ms__panel" id="msPanel">
      <div class="ms__panelHead">March 2026</div>
      <div class="ms__strip">
        <span class="ms__day">12</span><span class="ms__day">13</span><span class="ms__day ms__day--today">14</span><span class="ms__day">15</span><span class="ms__day">16</span>
      </div>
    </div>
  </div>
  <button type="button" class="ms__toggle" id="msToggle">Toggle width</button>
</div>
</main>

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

// 계산 겹: measureMode() 가 viewport 요소의 실측 폭(getBoundingClientRect)을 임계값과
// 비교해 popover(작은 카드)와 bottom-sheet(전체 폭) 두 형태 중 하나를 고른다.
@include stage($stage-orange);

.ms { position: relative; width: 100%; max-width: 230px; display: grid; gap: $sp-2; justify-items: center; }
.ms__viewport { position: relative; width: 200px; height: 168px; transition: width $dur-base $ease-spring; }
.ms__viewport--narrow { width: 92px; }
.ms__field {
  position: absolute; top: 0; left: 0; right: 0;
  display: grid; gap: $sp-1; padding: $sp-1 $sp-2;
  border: none; border-radius: $r-control;
  background: $subject-cream; color: $subject-ink; text-align: left; cursor: pointer;
  box-shadow: $shadow-raised;
}
.ms__fieldLabel { font-size: 8px; opacity: .68; }
.ms__fieldValue { font-size: 10px; font-weight: 700; }
.ms__panel {
  position: absolute;
  left: 0; right: 0; bottom: 0;
  box-sizing: border-box;
  padding: $sp-2;
  border-radius: $r-card $r-card 0 0;
  background: $stage-paper;
  box-shadow: $shadow-raised;
  transform: scaleY(0);
  transform-origin: bottom center;
  opacity: 0;
  pointer-events: none;
  transition: transform $dur-enter $ease-elastic, opacity $dur-quick $ease-out;
}
.ms__panel.ms--open.ms__panel--popover { transform: scale(.6, .46); opacity: 1; pointer-events: auto; }
.ms__panel.ms--open.ms__panel--sheet { transform: scale(1, 1); opacity: 1; pointer-events: auto; }
.ms__panelHead { font-size: 9px; font-weight: 700; color: $subject-ink; text-align: center; margin-bottom: $sp-1; }
.ms__strip { display: flex; gap: $sp-1; justify-content: center; }
.ms__day { display: grid; place-items: center; width: 18px; height: 18px; font-size: 9px; color: $subject-ink; border-radius: $r-xs; }
.ms__day--today { background: $subject-blue-deep; color: $subject-cream; font-weight: 700; }
.ms__toggle {
  border: none; border-radius: $r-pill; padding: $sp-1 $sp-3;
  font-size: 10px; font-weight: 700; color: $subject-ink; background: $subject-cream; cursor: pointer;
}

@media (max-width: 340px) {
  .ms { max-width: 170px; }
  .ms__viewport { width: 150px; height: 140px; }
  .ms__viewport--narrow { width: 76px; }
  .ms__day { width: 15px; height: 15px; font-size: 8px; }
}

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

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

.stage {
  box-sizing: border-box;
  min-height: 100vh;
  display: grid;
  place-items: center;
  margin: 0;
  background: #ff4d1f;
  font-family: -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  padding: clamp(8px, 4vw, 24px);
}

.ms {
  position: relative;
  width: 100%;
  max-width: 230px;
  display: grid;
  gap: 8px;
  justify-items: center;
}

.ms__viewport {
  position: relative;
  width: 200px;
  height: 168px;
  transition: width 300ms cubic-bezier(0.2, 0.8, 0.2, 1);
}

.ms__viewport--narrow {
  width: 92px;
}

.ms__field {
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  display: grid;
  gap: 4px;
  padding: 4px 8px;
  border: none;
  border-radius: 12px;
  background: #fff7e6;
  color: #17141a;
  text-align: left;
  cursor: pointer;
  box-shadow: 0 14px 24px rgba(23, 20, 26, 0.32);
}

.ms__fieldLabel {
  font-size: 8px;
  opacity: 0.68;
}

.ms__fieldValue {
  font-size: 10px;
  font-weight: 700;
}

.ms__panel {
  position: absolute;
  left: 0;
  right: 0;
  bottom: 0;
  box-sizing: border-box;
  padding: 8px;
  border-radius: 16px 16px 0 0;
  background: #ffffff;
  box-shadow: 0 14px 24px rgba(23, 20, 26, 0.32);
  transform: scaleY(0);
  transform-origin: bottom center;
  opacity: 0;
  pointer-events: none;
  transition: transform 600ms cubic-bezier(0.34, 1.56, 0.64, 1), opacity 220ms ease-out;
}

.ms__panel.ms--open.ms__panel--popover {
  transform: scale(0.6, 0.46);
  opacity: 1;
  pointer-events: auto;
}

.ms__panel.ms--open.ms__panel--sheet {
  transform: scale(1, 1);
  opacity: 1;
  pointer-events: auto;
}

.ms__panelHead {
  font-size: 9px;
  font-weight: 700;
  color: #17141a;
  text-align: center;
  margin-bottom: 4px;
}

.ms__strip {
  display: flex;
  gap: 4px;
  justify-content: center;
}

.ms__day {
  display: grid;
  place-items: center;
  width: 18px;
  height: 18px;
  font-size: 9px;
  color: #17141a;
  border-radius: 4px;
}

.ms__day--today {
  background: #0a4fe8;
  color: #fff7e6;
  font-weight: 700;
}

.ms__toggle {
  border: none;
  border-radius: 999px;
  padding: 4px 12px;
  font-size: 10px;
  font-weight: 700;
  color: #17141a;
  background: #fff7e6;
  cursor: pointer;
}

@media (max-width: 340px) {
  .ms {
    max-width: 170px;
  }
  .ms__viewport {
    width: 150px;
    height: 140px;
  }
  .ms__viewport--narrow {
    width: 76px;
  }
  .ms__day {
    width: 15px;
    height: 15px;
    font-size: 8px;
  }
}
@media (prefers-reduced-motion: reduce) {
  .ms__panel, .ms__viewport {
    transition: none;
  }
}

(function () {
  var THRESHOLD = 140; // px, 계산 겹: 이 폭 미만이면 바텀시트로 본다

  var ms = document.getElementById('ms');
  var viewport = document.getElementById('msViewport');
  var field = document.getElementById('msField');
  var panel = document.getElementById('msPanel');
  var toggleBtn = document.getElementById('msToggle');

  var wide = true;
  var open = false;

  function measureMode() {
    // 계산 겹: 뷰포트 요소의 실제 렌더 폭을 실측해 팝오버/시트 형태를 고른다
    var w = viewport.getBoundingClientRect().width;
    return w < THRESHOLD ? 'sheet' : 'popover';
  }

  function render() {
    var mode = measureMode();
    panel.classList.toggle('ms--open', open);
    panel.classList.toggle('ms__panel--sheet', mode === 'sheet');
    panel.classList.toggle('ms__panel--popover', mode === 'popover');
  }

  function human() {
    ms.classList.remove('is-demo');
    stopAutoplay();
  }

  field.addEventListener('click', function () {
    human();
    open = !open;
    render();
  });
  toggleBtn.addEventListener('click', function () {
    human();
    wide = !wide;
    viewport.classList.toggle('ms__viewport--narrow', !wide);
    open = true;
    render();
  });

  var steps = [
    function () { wide = true; viewport.classList.remove('ms__viewport--narrow'); open = true; },
    function () { wide = false; viewport.classList.add('ms__viewport--narrow'); open = true; },
    function () { open = false; },
    function () { wide = true; viewport.classList.remove('ms__viewport--narrow'); open = true; },
    function () { wide = false; viewport.classList.add('ms__viewport--narrow'); open = true; },
    function () { open = false; }
  ];
  var stepIdx = -1;
  var autoTimer = null;
  function stopAutoplay() { if (autoTimer) { clearInterval(autoTimer); autoTimer = null; } }
  function tick() {
    stepIdx = (stepIdx + 1) % steps.length;
    steps[stepIdx]();
    render();
  }

  render();
  var reduce = window.matchMedia('(prefers-reduced-motion: reduce)').matches;
  if (!reduce) { autoTimer = setInterval(tick, 620); }
})();

import { useEffect, useRef, useState } from 'react';
import styles from './DatePickerMobileSheetSwap.module.scss';

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

const THRESHOLD = 140; // px, 계산 겹: 이 폭 미만이면 바텀시트로 본다
const DAYS = [12, 13, 14, 15, 16];
const TODAY = 14;

export default function DatePickerMobileSheetSwap() {
  const viewportRef = useRef(null) as unknown as Box<HTMLDivElement>;
  const wideRef = useRef(true) as unknown as Box<boolean>;
  const openRef = useRef(false) as unknown as Box<boolean>;
  const [isDemo, setIsDemo] = useState(true);
  const [wide, setWide] = useState(true);
  const [open, setOpen] = useState(false);
  const [mode, setMode] = useState<'popover' | 'sheet'>('popover');

  function human() {
    setIsDemo(false);
  }

  function measureMode(): 'popover' | 'sheet' {
    // 계산 겹: 뷰포트 요소의 실제 렌더 폭을 실측해 팝오버/시트 형태를 고른다
    const el = viewportRef.current;
    if (!el) return 'popover';
    const w = el.getBoundingClientRect().width;
    return w < THRESHOLD ? 'sheet' : 'popover';
  }

  useEffect(() => {
    setMode(measureMode());
    // eslint-disable-next-line react-hooks/exhaustive-deps
  }, [wide]);

  useEffect(() => {
    const reduce = window.matchMedia('(prefers-reduced-motion: reduce)').matches;
    if (reduce) return;
    const steps: (() => void)[] = [
      () => { wideRef.current = true; openRef.current = true; setWide(true); setOpen(true); },
      () => { wideRef.current = false; openRef.current = true; setWide(false); setOpen(true); },
      () => { openRef.current = false; setOpen(false); },
      () => { wideRef.current = true; openRef.current = true; setWide(true); setOpen(true); },
      () => { wideRef.current = false; openRef.current = true; setWide(false); setOpen(true); },
      () => { openRef.current = false; setOpen(false); },
    ];
    let stepIdx = -1;
    const timer = window.setInterval(() => {
      if (!isDemo) return;
      stepIdx = (stepIdx + 1) % steps.length;
      steps[stepIdx]();
    }, 620);
    return () => window.clearInterval(timer);
    // eslint-disable-next-line react-hooks/exhaustive-deps
  }, [isDemo]);

  function onFieldClick() {
    human();
    setOpen((v) => !v);
  }
  function onToggleClick() {
    human();
    setWide((v) => !v);
    setOpen(true);
  }

  return (
    <div className={`${styles.ms} ${isDemo ? styles.isDemo : ''}`}>
      <div className={`${styles.msViewport} ${!wide ? styles.msViewportNarrow : ''}`} ref={viewportRef}>
        <button type="button" className={styles.msField} onClick={onFieldClick}>
          <span className={styles.msFieldLabel}>날짜</span>
          <span className={styles.msFieldValue}>2026년 3월 14일</span>
        </button>
        <div
          className={`${styles.msPanel} ${open ? styles.isOpen : ''} ${mode === 'sheet' ? styles.msPanelSheet : styles.msPanelPopover}`}
        >
          <div className={styles.msPanelHead}>2026년 3월</div>
          <div className={styles.msStrip}>
            {DAYS.map((d) => (
              <span key={d} className={`${styles.msDay} ${d === TODAY ? styles.msDayToday : ''}`}>{d}</span>
            ))}
          </div>
        </div>
      </div>
      <button type="button" className={styles.msToggle} onClick={onToggleClick}>폭 전환</button>
    </div>
  );
}