09Loading Button That Freezes to a Single Static Dot for Reduced Motion

<main class="stage">
<div class="scene is-demo" id="scene">
  <div class="togglePanel">
    <span class="toggleLabel" id="toggleLabel">Reduce motion preview</span>
    <button class="toggleSwitch" id="toggle" type="button" role="switch" aria-checked="false" aria-label="Reduce motion preview">
      <span class="toggleKnob" id="knob"></span>
    </button>
  </div>
  <button class="btn" id="btn" type="button">
    <span class="btnContent">
      <span class="btnLabel" id="label">Save</span>
      <span class="btnSpinnerWrap" id="spinnerWrap" aria-hidden="true"><span class="btnRing" id="ring"></span></span>
      <span class="btnDotWrap" id="dotWrap" aria-hidden="true"><span class="btnDot"></span></span>
    </span>
  </button>
  <span class="visuallyHidden" id="status" role="status" aria-live="polite"></span>
</div>
</main>

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

// 변수 3개
$duration: $dur-base;
$easing: $ease-out;
$color: $subject-blue-deep;

// 계산 겹: index.html 이 matchMedia 로 실제 OS 값을 읽어 시뮬 토글의 시작 상태로 삼고,
// 토글 상태에 따라 회전 스피너 루프 대신 정지된 점 하나를 고른다(둘 다 진짜 로딩 경로).
@include stage($stage-ink);

.scene {
  display: grid;
  place-items: center;
  gap: $sp-4;
}

.togglePanel {
  display: flex;
  align-items: center;
  gap: $sp-2;
  padding: $sp-2 $sp-3;
  border-radius: $r-pill;
  background: rgba($subject-cream, .08);
}

.toggleLabel {
  font-size: 11px;
  color: rgba($subject-cream, .78);
  white-space: nowrap;
}

.toggleSwitch {
  position: relative;
  width: 36px;
  height: 20px;
  padding: 4px;
  border: none;
  border-radius: $r-pill;
  background: rgba($subject-cream, .22);
  cursor: pointer;

  &[aria-checked="true"] { background: $subject-mint; }
  &:focus-visible { outline: 2px solid $subject-cream; outline-offset: 2px; }
}

.toggleKnob {
  display: block;
  width: 12px;
  height: 12px;
  border-radius: $r-pill;
  background: $subject-cream;
  transform: translateX(0px);
}

.btn {
  position: relative;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  height: 44px;
  padding: 0 $sp-5;
  border: none;
  border-radius: $r-control;
  background: $color;
  color: $subject-cream;
  font-weight: 600;
  font-size: 14px;
  line-height: 1;
  box-shadow: $shadow-press;
  cursor: pointer;

  &:focus-visible { outline: 2px solid $subject-cream; outline-offset: 3px; }
  &:disabled { cursor: default; }
}

.btnContent {
  position: relative;
  display: inline-flex;
  align-items: center;
  gap: $sp-2;
  height: 18px;
}

.btnSpinnerWrap,
.btnDotWrap {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 14px;
  height: 14px;
  opacity: 0;
}

.btnRing {
  width: 13px;
  height: 13px;
  border-radius: $r-pill;
  border: 2px solid rgba($subject-cream, .28);
  border-top-color: $subject-cream;
}

.btnDot {
  width: 6px;
  height: 6px;
  border-radius: $r-pill;
  background: $subject-cream;
}

.visuallyHidden {
  position: absolute;
  width: 1px;
  height: 1px;
  overflow: hidden;
  clip: rect(0 0 0 0);
  white-space: nowrap;
}

@media (max-width: 340px) {
  .btn { height: 40px; padding: 0 $sp-4; font-size: 13px; }
  .toggleLabel { font-size: 10px; }
}

@media (prefers-reduced-motion: reduce) {
  // 실사용 경로 적용 — index.html 이 osReduce 로 정지된 점 경로를 이미 고른다.
  // scss 만: 토글 노브의 남은 트랜지션을 꺼서 조작도 즉시 반영되게 한다.
  .toggleKnob { transition: none; }
}

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);
}

.scene {
  display: grid;
  place-items: center;
  gap: 16px;
}

.togglePanel {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 8px 12px;
  border-radius: 999px;
  background: rgba(255, 247, 230, 0.08);
}

.toggleLabel {
  font-size: 11px;
  color: rgba(255, 247, 230, 0.78);
  white-space: nowrap;
}

.toggleSwitch {
  position: relative;
  width: 36px;
  height: 20px;
  padding: 4px;
  border: none;
  border-radius: 999px;
  background: rgba(255, 247, 230, 0.22);
  cursor: pointer;
}
.toggleSwitch[aria-checked=true] {
  background: #4cd4a6;
}
.toggleSwitch:focus-visible {
  outline: 2px solid #fff7e6;
  outline-offset: 2px;
}

.toggleKnob {
  display: block;
  width: 12px;
  height: 12px;
  border-radius: 999px;
  background: #fff7e6;
  transform: translateX(0px);
}

.btn {
  position: relative;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  height: 44px;
  padding: 0 20px;
  border: none;
  border-radius: 12px;
  background: #0a4fe8;
  color: #fff7e6;
  font-weight: 600;
  font-size: 14px;
  line-height: 1;
  box-shadow: 0 6px 12px rgba(23, 20, 26, 0.32);
  cursor: pointer;
}
.btn:focus-visible {
  outline: 2px solid #fff7e6;
  outline-offset: 3px;
}
.btn:disabled {
  cursor: default;
}

.btnContent {
  position: relative;
  display: inline-flex;
  align-items: center;
  gap: 8px;
  height: 18px;
}

.btnSpinnerWrap,
.btnDotWrap {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 14px;
  height: 14px;
  opacity: 0;
}

.btnRing {
  width: 13px;
  height: 13px;
  border-radius: 999px;
  border: 2px solid rgba(255, 247, 230, 0.28);
  border-top-color: #fff7e6;
}

.btnDot {
  width: 6px;
  height: 6px;
  border-radius: 999px;
  background: #fff7e6;
}

.visuallyHidden {
  position: absolute;
  width: 1px;
  height: 1px;
  overflow: hidden;
  clip: rect(0 0 0 0);
  white-space: nowrap;
}

@media (max-width: 340px) {
  .btn {
    height: 40px;
    padding: 0 16px;
    font-size: 13px;
  }
  .toggleLabel {
    font-size: 10px;
  }
}
@media (prefers-reduced-motion: reduce) {
  .toggleKnob {
    transition: none;
  }
}

(function () {
  var FADE_MS = 180;
  var SPIN_MS = 900;
  var GAP_MS = 500;
  var START_DELAY_MS = 200;
  var TOGGLE_GAP_MS = 550;
  var DEG_PER_MS = 360 / 650;

  var scene = document.getElementById('scene');
  var btn = document.getElementById('btn');
  var label = document.getElementById('label');
  var spinnerWrap = document.getElementById('spinnerWrap');
  var ring = document.getElementById('ring');
  var dotWrap = document.getElementById('dotWrap');
  var status = document.getElementById('status');
  var toggle = document.getElementById('toggle');
  var knob = document.getElementById('knob');

  // 실제 OS 설정을 진짜로 읽는다 — 기본 상태는 이 값을 따른다.
  var mql = window.matchMedia('(prefers-reduced-motion: reduce)');
  var osReduce = mql.matches;
  var simReduce = osReduce;

  var gen = 0;
  var timers = [];
  var rafId = 0;

  function human() {
    if (scene.classList.contains('is-demo')) {
      scene.classList.remove('is-demo');
      timers.forEach(function (t) { clearTimeout(t); });
      timers = [];
    }
  }

  function setToggleUI() {
    toggle.setAttribute('aria-checked', simReduce ? 'true' : 'false');
    knob.style.transform = simReduce ? 'translateX(16px)' : 'translateX(0px)';
  }

  function applyToggle(next) {
    simReduce = next;
    setToggleUI();
  }

  // 시뮬 토글 — 방문자가 실제 OS 설정과 무관하게 두 상태를 미리 볼 수 있다.
  toggle.addEventListener('click', function () {
    human();
    applyToggle(!simReduce);
  });

  if (osReduce) setToggleUI();

  // 실사용 경로 적용 — 진짜 OS 값이 바뀌면(브라우저·OS 설정 변경) 시뮬 토글도 따라간다.
  function onOsChange(e) {
    osReduce = e.matches;
    applyToggle(osReduce);
  }
  if (mql.addEventListener) mql.addEventListener('change', onOsChange);

  function easeInOutQuad(p) { return p < .5 ? 2 * p * p : 1 - Math.pow(-2 * p + 2, 2) / 2; }

  function fade(el, from, to, ms, myGen, onDone) {
    var start = null;
    function step(now) {
      if (myGen !== gen) return;
      if (start === null) start = now;
      var p = Math.min(1, (now - start) / ms);
      el.style.opacity = String(from + (to - from) * easeInOutQuad(p));
      if (p < 1) requestAnimationFrame(step); else if (onDone) onDone();
    }
    requestAnimationFrame(step);
  }

  function spinLoop(myGen) {
    var start = null;
    function step(now) {
      if (myGen !== gen) return;
      if (start === null) start = now;
      var angle = ((now - start) * DEG_PER_MS) % 360;
      ring.style.transform = 'rotate(' + angle.toFixed(1) + 'deg)';
      rafId = requestAnimationFrame(step);
    }
    rafId = requestAnimationFrame(step);
  }

  function runLoad(myGen, useStaticDot, onDone) {
    btn.disabled = true;
    btn.setAttribute('aria-busy', 'true');
    status.textContent = 'Saving';
    if (useStaticDot) {
      dotWrap.style.opacity = '1';
    } else {
      fade(spinnerWrap, 0, 1, FADE_MS, myGen, function () { spinLoop(myGen); });
    }
    timers.push(setTimeout(function () {
      cancelAnimationFrame(rafId);
      dotWrap.style.opacity = '0';
      spinnerWrap.style.opacity = '0';
      btn.disabled = false;
      btn.removeAttribute('aria-busy');
      status.textContent = 'Saved';
      if (onDone) onDone();
    }, SPIN_MS));
  }

  btn.addEventListener('click', function () {
    if (btn.disabled) return;
    human();
    gen++;
    runLoad(gen, simReduce);
  });

  // reduce: 시연 게이트만 — 아래 자동 루프는 reduce 여부와 무관하게 두 상태를 번갈아 보여주려고
  // 계속 돈다(정지 표시 자체가 이 항목의 주제라 자동 루프를 완전히 끄면 데모가 항상 빈 화면이다).
  // 실사용 경로는 위 runLoad(simReduce) 가 osReduce 시작값을 그대로 물려받아 처리한다.
  function cycle() {
    if (!scene.classList.contains('is-demo')) return;
    gen++;
    var myGen = gen;
    var useStaticDot = simReduce;
    runLoad(myGen, useStaticDot, function () {
      timers.push(setTimeout(function () {
        if (!scene.classList.contains('is-demo')) return;
        applyToggle(!simReduce);
        timers.push(setTimeout(cycle, TOGGLE_GAP_MS));
      }, GAP_MS));
    });
  }

  timers.push(setTimeout(cycle, START_DELAY_MS));
})();

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

const FADE_MS = 180;
const SPIN_MS = 900;
const GAP_MS = 500;
const START_DELAY_MS = 200;
const TOGGLE_GAP_MS = 550;
const DEG_PER_MS = 360 / 650;

export default function ButtonLoadingReducedMotionStatic() {
  const sceneRef = useRef<HTMLDivElement>(null);
  const btnRef = useRef<HTMLButtonElement>(null);
  const labelRef = useRef<HTMLSpanElement>(null);
  const spinnerWrapRef = useRef<HTMLSpanElement>(null);
  const ringRef = useRef<HTMLSpanElement>(null);
  const dotWrapRef = useRef<HTMLSpanElement>(null);
  const statusRef = useRef<HTMLSpanElement>(null);
  const toggleRef = useRef<HTMLButtonElement>(null);
  const knobRef = useRef<HTMLSpanElement>(null);

  useEffect(() => {
    const scene = sceneRef.current;
    const btn = btnRef.current;
    const label = labelRef.current;
    const spinnerWrap = spinnerWrapRef.current;
    const ring = ringRef.current;
    const dotWrap = dotWrapRef.current;
    const status = statusRef.current;
    const toggle = toggleRef.current;
    const knob = knobRef.current;
    if (!scene || !btn || !label || !spinnerWrap || !ring || !dotWrap || !status || !toggle || !knob) return undefined;

    // 실제 OS 설정을 진짜로 읽는다 — 기본 상태는 이 값을 따른다.
    const mql = window.matchMedia('(prefers-reduced-motion: reduce)');
    let osReduce = mql.matches;
    let simReduce = osReduce;

    let gen = 0;
    let timers: number[] = [];
    let rafId = 0;

    function human() {
      if (scene!.classList.contains(styles['is-demo'])) {
        scene!.classList.remove(styles['is-demo']);
        timers.forEach((t) => window.clearTimeout(t));
        timers = [];
      }
    }

    function setToggleUI() {
      toggle!.setAttribute('aria-checked', simReduce ? 'true' : 'false');
      knob!.style.transform = simReduce ? 'translateX(16px)' : 'translateX(0px)';
    }

    function applyToggle(next: boolean) {
      simReduce = next;
      setToggleUI();
    }

    // 시뮬 토글 — 방문자가 실제 OS 설정과 무관하게 두 상태를 미리 볼 수 있다.
    function onToggleClick() {
      human();
      applyToggle(!simReduce);
    }
    toggle.addEventListener('click', onToggleClick);

    if (osReduce) setToggleUI();

    // 실사용 경로 적용 — 진짜 OS 값이 바뀌면(브라우저·OS 설정 변경) 시뮬 토글도 따라간다.
    function onOsChange(e: MediaQueryListEvent) {
      osReduce = e.matches;
      applyToggle(osReduce);
    }
    if (mql.addEventListener) mql.addEventListener('change', onOsChange);

    function easeInOutQuad(p: number) { return p < .5 ? 2 * p * p : 1 - Math.pow(-2 * p + 2, 2) / 2; }

    function fade(el: HTMLElement, from: number, to: number, ms: number, myGen: number, onDone?: () => void) {
      let start: number | null = null;
      function step(now: number) {
        if (myGen !== gen) return;
        if (start === null) start = now;
        const p = Math.min(1, (now - start) / ms);
        el.style.opacity = String(from + (to - from) * easeInOutQuad(p));
        if (p < 1) requestAnimationFrame(step); else if (onDone) onDone();
      }
      requestAnimationFrame(step);
    }

    function spinLoop(myGen: number) {
      let start: number | null = null;
      function step(now: number) {
        if (myGen !== gen) return;
        if (start === null) start = now;
        const angle = ((now - start) * DEG_PER_MS) % 360;
        ring!.style.transform = 'rotate(' + angle.toFixed(1) + 'deg)';
        rafId = requestAnimationFrame(step);
      }
      rafId = requestAnimationFrame(step);
    }

    function runLoad(myGen: number, useStaticDot: boolean, onDone?: () => void) {
      btn!.disabled = true;
      btn!.setAttribute('aria-busy', 'true');
      status!.textContent = '저장하는 중';
      if (useStaticDot) {
        dotWrap!.style.opacity = '1';
      } else {
        fade(spinnerWrap!, 0, 1, FADE_MS, myGen, () => { spinLoop(myGen); });
      }
      timers.push(window.setTimeout(() => {
        cancelAnimationFrame(rafId);
        dotWrap!.style.opacity = '0';
        spinnerWrap!.style.opacity = '0';
        btn!.disabled = false;
        btn!.removeAttribute('aria-busy');
        status!.textContent = '저장 완료';
        if (onDone) onDone();
      }, SPIN_MS));
    }

    function onClick() {
      if (btn!.disabled) return;
      human();
      gen++;
      runLoad(gen, simReduce);
    }
    btn.addEventListener('click', onClick);

    // reduce: 시연 게이트만 — 아래 자동 루프는 reduce 여부와 무관하게 두 상태를 번갈아 보여주려고
    // 계속 돈다(정지 표시 자체가 이 항목의 주제라 자동 루프를 완전히 끄면 데모가 항상 빈 화면이다).
    // 실사용 경로는 위 runLoad(simReduce) 가 osReduce 시작값을 그대로 물려받아 처리한다.
    function cycle() {
      if (!scene!.classList.contains(styles['is-demo'])) return;
      gen++;
      const myGen = gen;
      const useStaticDot = simReduce;
      runLoad(myGen, useStaticDot, () => {
        timers.push(window.setTimeout(() => {
          if (!scene!.classList.contains(styles['is-demo'])) return;
          applyToggle(!simReduce);
          timers.push(window.setTimeout(cycle, TOGGLE_GAP_MS));
        }, GAP_MS));
      });
    }

    timers.push(window.setTimeout(cycle, START_DELAY_MS));

    return () => {
      btn.removeEventListener('click', onClick);
      toggle.removeEventListener('click', onToggleClick);
      if (mql.removeEventListener) mql.removeEventListener('change', onOsChange);
      timers.forEach((t) => window.clearTimeout(t));
      cancelAnimationFrame(rafId);
    };
  }, []);

  return (
    <main className={styles.stage}>
      <div className={styles.scene + ' ' + styles['is-demo']} ref={sceneRef}>
        <div className={styles.togglePanel}>
          <span className={styles.toggleLabel}>Reduce motion preview</span>
          <button
            className={styles.toggleSwitch}
            ref={toggleRef}
            type="button"
            role="switch"
            aria-checked="false"
            aria-label="Reduce motion preview"
          >
            <span className={styles.toggleKnob} ref={knobRef} />
          </button>
        </div>
        <button className={styles.btn} ref={btnRef} type="button">
          <span className={styles.btnContent}>
            <span className={styles.btnLabel} ref={labelRef}>Save</span>
            <span className={styles.btnSpinnerWrap} ref={spinnerWrapRef} aria-hidden="true">
              <span className={styles.btnRing} ref={ringRef} />
            </span>
            <span className={styles.btnDotWrap} ref={dotWrapRef} aria-hidden="true">
              <span className={styles.btnDot} />
            </span>
          </span>
        </button>
        <span className={styles.visuallyHidden} ref={statusRef} role="status" aria-live="polite" />
      </div>
    </main>
  );
}