05Button That Collapses to Icon-Only Width While Loading

<main class="stage">
<div class="scene is-demo" id="scene">
  <button class="btn" id="btn" type="button">
    <span class="btnIcon" id="icon" aria-hidden="true">
      <svg viewBox="0 0 256 256" width="18" height="18">
        <g fill="currentColor"><path d="m216 128l-72 72V56Z" opacity=".2"/><path d="m221.66 122.34l-72-72A8 8 0 0 0 136 56v64H40a8 8 0 0 0 0 16h96v64a8 8 0 0 0 13.66 5.66l72-72a8 8 0 0 0 0-11.32M152 180.69V75.31L204.69 128Z"/></g>
      </svg>
    </span>
    <span class="btnLabel" id="label">Send message</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 의 driveScale() 이 실측 폭 대비 목표(아이콘 한 칸) 비율을 구해 매 프레임
// btn 을 scaleX 로 줄이고, 아이콘엔 1/scale 역스케일을 걸어 눌림을 상쇄한다.
@include stage($stage-ink);

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

.btn {
  position: relative;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: $sp-2;
  height: 44px;
  min-width: 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;
  will-change: transform;

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

.btnIcon {
  display: flex;
  flex: 0 0 auto;
  align-items: center;
  justify-content: center;
}

.btnLabel {
  white-space: nowrap;
}

.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; }
}

@media (prefers-reduced-motion: reduce) {
  // 실사용 경로 적용 — index.html 의 runReduced() 가 scaleX 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: #17141a;
  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;
  gap: 8px;
  height: 44px;
  min-width: 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;
  will-change: transform;
}
.btn:focus-visible {
  outline: 2px solid #fff7e6;
  outline-offset: 3px;
}
.btn:disabled {
  cursor: default;
}

.btnIcon {
  display: flex;
  flex: 0 0 auto;
  align-items: center;
  justify-content: center;
}

.btnLabel {
  white-space: nowrap;
}

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

(function () {
  var COLLAPSE_MS = 380;
  var LABEL_FADE_MS = 150;
  var HOLD_MS = 700;
  var EXPAND_MS = 380;
  var GAP_MS = 450;
  var START_DELAY_MS = 200;
  var COLLAPSED_WIDTH_PX = 44;

  var scene = document.getElementById('scene');
  var btn = document.getElementById('btn');
  var icon = document.getElementById('icon');
  var label = document.getElementById('label');
  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 easeInOutQuad(p) { return p < .5 ? 2 * p * p : 1 - Math.pow(-2 * p + 2, 2) / 2; }

  // 계산 겹: 지금 렌더된 버튼 실측 폭(fullWidth)과 아이콘 하나가 들어갈 목표 폭을 비교해
  // collapsedRatio 를 구하고, 매 프레임 scale 값으로 btn 을 scaleX 하면서 아이콘엔 1/scale
  // 역스케일을 걸어 버튼이 좁아지는 동안에도 아이콘 자체는 눌리지 않게 만든다.
  function driveScale(myGen, fromScale, toScale, ms, onDone) {
    var fullWidth = btn.getBoundingClientRect().width / fromScale;
    var collapsedRatio = COLLAPSED_WIDTH_PX / fullWidth;
    var resolvedFrom = fromScale === 1 ? 1 : collapsedRatio;
    var resolvedTo = toScale === 1 ? 1 : collapsedRatio;
    var start = null;
    function step(now) {
      if (myGen !== gen) return;
      if (start === null) start = now;
      var p = easeInOutQuad(Math.min(1, (now - start) / ms));
      var scale = resolvedFrom + (resolvedTo - resolvedFrom) * p;
      btn.style.transform = 'scaleX(' + scale.toFixed(4) + ')';
      icon.style.transform = 'scaleX(' + (1 / scale).toFixed(4) + ')';
      if (p < 1) requestAnimationFrame(step); else onDone();
    }
    requestAnimationFrame(step);
  }

  function fade(el, from, to, ms, myGen) {
    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) * p);
      if (p < 1) requestAnimationFrame(step);
    }
    requestAnimationFrame(step);
  }

  function reset() {
    btn.style.transform = 'scaleX(1)';
    icon.style.transform = 'scaleX(1)';
    label.style.opacity = '1';
  }

  function runAnimated() {
    gen++;
    var myGen = gen;
    btn.disabled = true;
    btn.setAttribute('aria-busy', 'true');
    status.textContent = 'Sending';
    fade(label, 1, 0, LABEL_FADE_MS, myGen);
    driveScale(myGen, 1, 0, COLLAPSE_MS, function () {
      timers.push(setTimeout(function () {
        status.textContent = 'Sent';
        driveScale(myGen, 0, 1, EXPAND_MS, function () {
          fade(label, 0, 1, LABEL_FADE_MS, myGen);
          btn.disabled = false;
          btn.removeAttribute('aria-busy');
        });
      }, HOLD_MS));
    });
  }

  function runReduced() {
    gen++;
    btn.disabled = true;
    btn.setAttribute('aria-busy', 'true');
    status.textContent = 'Sending';
    var fullWidth = btn.getBoundingClientRect().width;
    var collapsedRatio = COLLAPSED_WIDTH_PX / fullWidth;
    label.style.opacity = '0';
    btn.style.transform = 'scaleX(' + collapsedRatio.toFixed(4) + ')';
    icon.style.transform = 'scaleX(' + (1 / collapsedRatio).toFixed(4) + ')';
    timers.push(setTimeout(function () {
      status.textContent = 'Sent';
      reset();
      btn.disabled = false;
      btn.removeAttribute('aria-busy');
    }, HOLD_MS));
  }

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

  // reduce: 실사용 경로 적용 — runReduced() 는 scaleX 트윈 없이 즉시 좁아지고 즉시 되돌아간다.
  // 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));
    }, COLLAPSE_MS + HOLD_MS + EXPAND_MS));
  }

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

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

const COLLAPSE_MS = 380;
const LABEL_FADE_MS = 150;
const HOLD_MS = 700;
const EXPAND_MS = 380;
const GAP_MS = 450;
const START_DELAY_MS = 200;
const COLLAPSED_WIDTH_PX = 44;

export default function ButtonLoadingIconOnlyCollapse() {
  const sceneRef = useRef<HTMLDivElement>(null);
  const btnRef = useRef<HTMLButtonElement>(null);
  const iconRef = useRef<HTMLSpanElement>(null);
  const labelRef = useRef<HTMLSpanElement>(null);
  const statusRef = useRef<HTMLSpanElement>(null);

  useEffect(() => {
    const scene = sceneRef.current;
    const btn = btnRef.current;
    const icon = iconRef.current;
    const label = labelRef.current;
    const status = statusRef.current;
    if (!scene || !btn || !icon || !label || !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 easeInOutQuad(p: number) { return p < .5 ? 2 * p * p : 1 - Math.pow(-2 * p + 2, 2) / 2; }

    // 계산 겹: 지금 렌더된 버튼 실측 폭(fullWidth)과 아이콘 하나가 들어갈 목표 폭을 비교해
    // collapsedRatio 를 구하고, 매 프레임 scale 값으로 btn 을 scaleX 하면서 아이콘엔 1/scale
    // 역스케일을 걸어 버튼이 좁아지는 동안에도 아이콘 자체는 눌리지 않게 만든다.
    function driveScale(myGen: number, fromScale: number, toScale: number, ms: number, onDone: () => void) {
      const fullWidth = btn!.getBoundingClientRect().width / fromScale;
      const collapsedRatio = COLLAPSED_WIDTH_PX / fullWidth;
      const resolvedFrom = fromScale === 1 ? 1 : collapsedRatio;
      const resolvedTo = toScale === 1 ? 1 : collapsedRatio;
      let start: number | null = null;
      function step(now: number) {
        if (myGen !== gen) return;
        if (start === null) start = now;
        const p = easeInOutQuad(Math.min(1, (now - start) / ms));
        const scale = resolvedFrom + (resolvedTo - resolvedFrom) * p;
        btn!.style.transform = 'scaleX(' + scale.toFixed(4) + ')';
        icon!.style.transform = 'scaleX(' + (1 / scale).toFixed(4) + ')';
        if (p < 1) requestAnimationFrame(step); else onDone();
      }
      requestAnimationFrame(step);
    }

    function fade(el: HTMLElement, from: number, to: number, ms: number, myGen: number) {
      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) * p);
        if (p < 1) requestAnimationFrame(step);
      }
      requestAnimationFrame(step);
    }

    function reset() {
      btn!.style.transform = 'scaleX(1)';
      icon!.style.transform = 'scaleX(1)';
      label!.style.opacity = '1';
    }

    function runAnimated() {
      gen++;
      const myGen = gen;
      btn!.disabled = true;
      btn!.setAttribute('aria-busy', 'true');
      status!.textContent = '전송하는 중';
      fade(label!, 1, 0, LABEL_FADE_MS, myGen);
      driveScale(myGen, 1, 0, COLLAPSE_MS, () => {
        timers.push(window.setTimeout(() => {
          status!.textContent = '전송 완료';
          driveScale(myGen, 0, 1, EXPAND_MS, () => {
            fade(label!, 0, 1, LABEL_FADE_MS, myGen);
            btn!.disabled = false;
            btn!.removeAttribute('aria-busy');
          });
        }, HOLD_MS));
      });
    }

    function runReduced() {
      gen++;
      btn!.disabled = true;
      btn!.setAttribute('aria-busy', 'true');
      status!.textContent = '전송하는 중';
      const fullWidth = btn!.getBoundingClientRect().width;
      const collapsedRatio = COLLAPSED_WIDTH_PX / fullWidth;
      label!.style.opacity = '0';
      btn!.style.transform = 'scaleX(' + collapsedRatio.toFixed(4) + ')';
      icon!.style.transform = 'scaleX(' + (1 / collapsedRatio).toFixed(4) + ')';
      timers.push(window.setTimeout(() => {
        status!.textContent = '전송 완료';
        reset();
        btn!.disabled = false;
        btn!.removeAttribute('aria-busy');
      }, HOLD_MS));
    }

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

    // reduce: 실사용 경로 적용 — runReduced() 는 scaleX 트윈 없이 즉시 좁아지고 즉시 되돌아간다.
    // 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));
      }, COLLAPSE_MS + HOLD_MS + EXPAND_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.btnIcon} ref={iconRef} aria-hidden="true">
            <svg viewBox="0 0 256 256" width="18" height="18">
              <g fill="currentColor">
                <path d="m216 128l-72 72V56Z" opacity=".2" />
                <path d="m221.66 122.34l-72-72A8 8 0 0 0 136 56v64H40a8 8 0 0 0 0 16h96v64a8 8 0 0 0 13.66 5.66l72-72a8 8 0 0 0 0-11.32M152 180.69V75.31L204.69 128Z" />
              </g>
            </svg>
          </span>
          <span className={styles.btnLabel} ref={labelRef}>Send message</span>
        </button>
        <span className={styles.visuallyHidden} ref={statusRef} role="status" aria-live="polite" />
      </div>
    </main>
  );
}