02ボタンの背景が進捗分だけ満ちるミニプログレス表示

<main class="stage">
<div class="scene is-demo" id="scene">
  <button class="btn" id="btn" type="button">
    <span class="btnFill" id="fill" aria-hidden="true"></span>
    <span class="btnText" id="text">Upload file</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-enter;
$easing: $ease-out;
$color: $subject-blue-deep;

// 계산 겹: index.html 의 drive() 가 easeOutCubic 진행률을 매 프레임 계산해 채움 막대의
// scaleX 와 라벨 퍼센트 숫자를 같은 값으로 동시에 갱신한다.
@include stage($stage-yellow);

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

.btn {
  position: relative;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-width: 168px;
  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;
  overflow: hidden;

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

.btnFill {
  position: absolute;
  inset: 0;
  transform: scaleX(0);
  transform-origin: left center; // 채움 막대가 시작 변에서 자란다 — BD 예외 규칙
  background: rgba($subject-cream, .24);
}

.btnText {
  position: relative;
  z-index: 1;
  white-space: nowrap;
  font-variant-numeric: tabular-nums;
}

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

@media (max-width: 340px) {
  .btn { min-width: 148px; height: 40px; padding: 0 $sp-4; font-size: 13px; }
}

@media (prefers-reduced-motion: reduce) {
  // 실사용 경로 적용 — index.html 의 runReduced() 가 채움 트윈 없이 즉시 값을 바꾼다.
  // scss 만: 남은 트랜지션을 전부 끈다.
  * { 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: #ffd23f;
  font-family: -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  padding: clamp(8px, 4vw, 24px);
}

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

.btn {
  position: relative;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-width: 168px;
  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;
  overflow: hidden;
}
.btn:focus-visible {
  outline: 2px solid #17141a;
  outline-offset: 3px;
}
.btn:disabled {
  cursor: default;
}

.btnFill {
  position: absolute;
  inset: 0;
  transform: scaleX(0);
  transform-origin: left center;
  background: rgba(255, 247, 230, 0.24);
}

.btnText {
  position: relative;
  z-index: 1;
  white-space: nowrap;
  font-variant-numeric: tabular-nums;
}

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

@media (max-width: 340px) {
  .btn {
    min-width: 148px;
    height: 40px;
    padding: 0 16px;
    font-size: 13px;
  }
}
@media (prefers-reduced-motion: reduce) {
  * {
    transition: none !important;
  }
}

(function () {
  var FILL_MS = 1100;
  var HOLD_AT_FULL_MS = 500;
  var SUCCESS_HOLD_MS = 350;
  var GAP_MS = 450;
  var START_DELAY_MS = 200;

  var scene = document.getElementById('scene');
  var btn = document.getElementById('btn');
  var fill = document.getElementById('fill');
  var text = document.getElementById('text');
  var status = document.getElementById('status');
  var reduce = window.matchMedia('(prefers-reduced-motion: reduce)').matches;

  var gen = 0;
  var timers = [];

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

  function easeOutCubic(p) { return 1 - Math.pow(1 - p, 3); }

  // 계산 겹: 채움 막대는 scaleX 로만 늘어난다(transform-origin: left — 시작 변에서 자란다는
  // 예외적 origin, 채움 막대이므로 허용). 진행률 p 는 easeOutCubic 으로 매 프레임 계산해
  // 같은 값을 style.transform 과 라벨의 퍼센트 숫자 둘 다에 쓴다.
  function drive(myGen, onDone) {
    var start = null;
    function step(now) {
      if (myGen !== gen) return;
      if (start === null) start = now;
      var raw = Math.min(1, (now - start) / FILL_MS);
      var p = easeOutCubic(raw);
      fill.style.transform = 'scaleX(' + p.toFixed(4) + ')';
      text.textContent = 'Uploading ' + Math.round(p * 100) + '%';
      if (raw < 1) requestAnimationFrame(step); else onDone();
    }
    requestAnimationFrame(step);
  }

  function fadeOutFill(myGen, ms, onDone) {
    var start = null;
    function step(now) {
      if (myGen !== gen) return;
      if (start === null) start = now;
      var p = Math.min(1, (now - start) / ms);
      fill.style.opacity = String(1 - p);
      if (p < 1) requestAnimationFrame(step); else onDone();
    }
    requestAnimationFrame(step);
  }

  function runAnimated() {
    gen++;
    var myGen = gen;
    btn.disabled = true;
    btn.setAttribute('aria-busy', 'true');
    status.textContent = 'アップロード中';
    fill.style.opacity = '1';
    fill.style.transform = 'scaleX(0)';
    drive(myGen, function () {
      timers.push(setTimeout(function () {
        text.textContent = 'Uploaded';
        status.textContent = 'アップロード完了';
        fadeOutFill(myGen, 260, function () {
          timers.push(setTimeout(function () {
            btn.disabled = false;
            btn.removeAttribute('aria-busy');
            text.textContent = 'Upload file';
            fill.style.transform = 'scaleX(0)';
          }, SUCCESS_HOLD_MS));
        });
      }, HOLD_AT_FULL_MS));
    });
  }

  function runReduced() {
    gen++;
    btn.disabled = true;
    btn.setAttribute('aria-busy', 'true');
    status.textContent = 'アップロード中';
    fill.style.opacity = '1';
    fill.style.transform = 'scaleX(1)';
    text.textContent = 'Uploading 100%';
    timers.push(setTimeout(function () {
      text.textContent = 'Uploaded';
      status.textContent = 'アップロード完了';
      fill.style.opacity = '0';
      timers.push(setTimeout(function () {
        btn.disabled = false;
        btn.removeAttribute('aria-busy');
        text.textContent = 'Upload file';
        fill.style.transform = 'scaleX(0)';
      }, SUCCESS_HOLD_MS));
    }, HOLD_AT_FULL_MS));
  }

  btn.addEventListener('click', function () {
    if (btn.disabled) return;
    human();
    if (reduce) runReduced(); else runAnimated();
  });

  // reduce: 실사용 경로 적용 — runReduced() 는 채움 트윈 없이 즉시 꽉 찬 상태로 바꾼다.
  // 아래 자동 루프는 시연 게이트만 — reduce 에서는 돌지 않는다.
  function cycle() {
    if (!scene.classList.contains('is-demo')) return;
    runAnimated();
    timers.push(setTimeout(function () {
      timers.push(setTimeout(cycle, GAP_MS));
    }, FILL_MS + HOLD_AT_FULL_MS + 260 + SUCCESS_HOLD_MS));
  }

  if (!reduce) {
    timers.push(setTimeout(cycle, START_DELAY_MS));
  }
})();

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

const FILL_MS = 1100;
const HOLD_AT_FULL_MS = 500;
const SUCCESS_HOLD_MS = 350;
const GAP_MS = 450;
const START_DELAY_MS = 200;

export default function ButtonLoadingProgressFill() {
  const sceneRef = useRef<HTMLDivElement>(null);
  const btnRef = useRef<HTMLButtonElement>(null);
  const fillRef = useRef<HTMLSpanElement>(null);
  const textRef = useRef<HTMLSpanElement>(null);
  const statusRef = useRef<HTMLSpanElement>(null);

  useEffect(() => {
    const scene = sceneRef.current;
    const btn = btnRef.current;
    const fill = fillRef.current;
    const text = textRef.current;
    const status = statusRef.current;
    if (!scene || !btn || !fill || !text || !status) return undefined;
    const reduce = window.matchMedia('(prefers-reduced-motion: reduce)').matches;

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

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

    function easeOutCubic(p: number) { return 1 - Math.pow(1 - p, 3); }

    // 계산 겹: 채움 막대는 scaleX 로만 늘어난다(transform-origin: left — 시작 변에서 자란다는
    // 예외적 origin, 채움 막대이므로 허용). 진행률 p 는 easeOutCubic 으로 매 프레임 계산해
    // 같은 값을 style.transform 과 라벨의 퍼센트 숫자 둘 다에 쓴다.
    function drive(myGen: number, onDone: () => void) {
      let start: number | null = null;
      function step(now: number) {
        if (myGen !== gen) return;
        if (start === null) start = now;
        const raw = Math.min(1, (now - start) / FILL_MS);
        const p = easeOutCubic(raw);
        fill!.style.transform = 'scaleX(' + p.toFixed(4) + ')';
        text!.textContent = 'Uploading ' + Math.round(p * 100) + '%';
        if (raw < 1) requestAnimationFrame(step); else onDone();
      }
      requestAnimationFrame(step);
    }

    function fadeOutFill(myGen: number, ms: 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);
        fill!.style.opacity = String(1 - p);
        if (p < 1) requestAnimationFrame(step); else onDone();
      }
      requestAnimationFrame(step);
    }

    function runAnimated() {
      gen++;
      const myGen = gen;
      btn!.disabled = true;
      btn!.setAttribute('aria-busy', 'true');
      status!.textContent = '업로드하는 중';
      fill!.style.opacity = '1';
      fill!.style.transform = 'scaleX(0)';
      drive(myGen, () => {
        timers.push(window.setTimeout(() => {
          text!.textContent = 'Uploaded';
          status!.textContent = '업로드 완료';
          fadeOutFill(myGen, 260, () => {
            timers.push(window.setTimeout(() => {
              btn!.disabled = false;
              btn!.removeAttribute('aria-busy');
              text!.textContent = 'Upload file';
              fill!.style.transform = 'scaleX(0)';
            }, SUCCESS_HOLD_MS));
          });
        }, HOLD_AT_FULL_MS));
      });
    }

    function runReduced() {
      gen++;
      btn!.disabled = true;
      btn!.setAttribute('aria-busy', 'true');
      status!.textContent = '업로드하는 중';
      fill!.style.opacity = '1';
      fill!.style.transform = 'scaleX(1)';
      text!.textContent = 'Uploading 100%';
      timers.push(window.setTimeout(() => {
        text!.textContent = 'Uploaded';
        status!.textContent = '업로드 완료';
        fill!.style.opacity = '0';
        timers.push(window.setTimeout(() => {
          btn!.disabled = false;
          btn!.removeAttribute('aria-busy');
          text!.textContent = 'Upload file';
          fill!.style.transform = 'scaleX(0)';
        }, SUCCESS_HOLD_MS));
      }, HOLD_AT_FULL_MS));
    }

    function onClick() {
      if (btn!.disabled) return;
      human();
      if (reduce) runReduced(); else runAnimated();
    }
    btn.addEventListener('click', onClick);

    // reduce: 실사용 경로 적용 — runReduced() 는 채움 트윈 없이 즉시 값을 바꾼다.
    // 아래 자동 루프는 시연 게이트만 — reduce 에서는 돌지 않는다.
    function cycle() {
      if (!scene!.classList.contains(styles['is-demo'])) return;
      runAnimated();
      timers.push(window.setTimeout(() => {
        timers.push(window.setTimeout(cycle, GAP_MS));
      }, FILL_MS + HOLD_AT_FULL_MS + 260 + SUCCESS_HOLD_MS));
    }

    if (!reduce) {
      timers.push(window.setTimeout(cycle, START_DELAY_MS));
    }

    return () => {
      btn.removeEventListener('click', onClick);
      timers.forEach((t) => window.clearTimeout(t));
    };
  }, []);

  return (
    <main className={styles.stage}>
      <div className={styles.scene + ' ' + styles['is-demo']} ref={sceneRef}>
        <button className={styles.btn} ref={btnRef} type="button">
          <span className={styles.btnFill} ref={fillRef} aria-hidden="true" />
          <span className={styles.btnText} ref={textRef}>Upload file</span>
        </button>
        <span className={styles.visuallyHidden} ref={statusRef} role="status" aria-live="polite" />
      </div>
    </main>
  );
}