02Warning Badge That Springs Up When Caps Lock Is On

<main class="stage">
<div class="pcs is-demo" id="pcsRoot">
  <form class="pcs__form" id="pcsForm" novalidate>
    <label class="pcs__field">
      <span class="pcs__labelRow">
        <span class="pcs__labelText">Password</span>
        <span class="pcs__badge" id="pcsBadge" role="status">
          <svg class="pcs__badgeIcon" width="1em" height="1em" viewBox="0 0 256 256" aria-hidden="true"><g fill="currentColor"><path d="M224 128a96 96 0 1 1-96-96a96 96 0 0 1 96 96" opacity=".2"/><path d="M128 24a104 104 0 1 0 104 104A104.11 104.11 0 0 0 128 24m0 192a88 88 0 1 1 88-88a88.1 88.1 0 0 1-88 88m-8-80V80a8 8 0 0 1 16 0v56a8 8 0 0 1-16 0m20 36a12 12 0 1 1-12-12a12 12 0 0 1 12 12"/></g></svg>
          <span class="pcs__badgeText">Caps Lock</span>
        </span>
        <span class="pcs__srAnnounce" id="pcsAnnounce" aria-live="polite"></span>
      </span>
      <span class="pcs__inputWrap">
        <input class="pcs__input" id="pcsInput" type="password" autocomplete="new-password" spellcheck="false" value="">
        <button class="pcs__toggle" id="pcsToggle" type="button" aria-pressed="false" aria-label="Show password">
          <svg class="pcs__eyeShow" viewBox="0 0 24 24" width="20" height="20" aria-hidden="true">
            <path d="M2,12 C5,6 9,4 12,4 C15,4 19,6 22,12 C19,18 15,20 12,20 C9,20 5,18 2,12 Z" fill="none" stroke="currentColor" stroke-width="2"/>
            <circle cx="12" cy="12" r="3.2" fill="currentColor"/>
          </svg>
          <svg class="pcs__eyeHide" viewBox="0 0 24 24" width="20" height="20" aria-hidden="true">
            <path d="M2,12 Q12,4 22,12" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round"/>
            <path d="M2,12 Q12,20 22,12" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round"/>
          </svg>
        </button>
      </span>
    </label>
  </form>
</div>
</main>

@use "../../../../site/static/demo-tokens" as *;
@include stage($stage-yellow);

// 계산 겹: 배지 pos 는 언더댐프 스프링 적분(가속도=강성*오차-감쇠*속도)으로 매 프레임 갱신되고,
// pos 가 1 을 넘는 구간(overshoot)만큼 CAPSLOCK_BADGE_OVERSHOOT_PX 를 곱해 튀어 오르는 높이를 만든다.
// 실제 CapsLock 상태는 input 의 keydown/keyup 이벤트에서 getModifierState 로 읽는다.
.pcs {
  position: relative;
  width: min(92vw, calc(160vh - 12.8vw));
  aspect-ratio: 480 / 300;
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: center;
}

.pcs__form {
  width: 100%;
  max-width: 320px;
  box-sizing: border-box;
}

.pcs__field {
  display: grid;
  gap: $sp-2;
}

.pcs__labelRow {
  display: flex;
  align-items: center;
  gap: $sp-2;
  min-height: 26px;
}

.pcs__labelText {
  color: rgba($subject-ink, .82);
  font-weight: 600;
  font-size: 13px;
  line-height: 1.3;
}

.pcs__badge {
  display: inline-flex;
  align-items: center;
  gap: $sp-1;
  padding: $sp-1 $sp-2;
  border-radius: $r-xs;
  background: $stage-paper;
  color: $subject-ink;
  font-weight: 700;
  font-size: 11px;
  line-height: 1.4;
  opacity: 0;
  transform: translateY(14px) scale(.86);
  transform-origin: left center;
  will-change: transform, opacity;
}

.pcs__badge--active {
  box-shadow: $shadow-press;
}

.pcs__badgeIcon {
  flex: 0 0 auto;
  color: $subject-orange-deep;
}

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

.pcs__inputWrap {
  position: relative;
  display: flex;
  align-items: center;
}

.pcs__input {
  width: 100%;
  box-sizing: border-box;
  padding: $sp-3 $sp-10 $sp-3 $sp-4;
  border-radius: $r-control;
  border: 0;
  background: rgba($subject-ink, .06);
  color: $subject-ink;
  caret-color: $subject-ink;
  font-weight: 500;
  font-size: 17px;
  line-height: 1.3;
  letter-spacing: .06em;

  &:focus { outline: 2px solid $subject-blue; outline-offset: 2px; }
}

.pcs__toggle {
  position: absolute;
  right: $sp-2;
  top: 50%;
  transform: translateY(-50%);
  width: 36px;
  height: 36px;
  display: grid;
  place-items: center;
  border: 0;
  border-radius: $r-pill;
  background: transparent;
  color: rgba($subject-ink, .78);
  cursor: pointer;

  &:hover { background: rgba($subject-ink, .08); }
  &:focus-visible { outline: 2px solid $subject-blue; outline-offset: 2px; }
}

.pcs__eyeHide { display: none; }
.pcs--revealed .pcs__eyeShow { display: none; }
.pcs--revealed .pcs__eyeHide { display: block; }

// 배경 톤: Caps Lock 경고를 배지 하나에 가두지 않고 카드 톤 전체로 넓힌다(계산 추가 없이 기존 신호 재사용).
.pcs::before {
  content: "";
  position: absolute;
  inset: 0;
  pointer-events: none;
  background: rgba(201, 48, 0, 0);
  transition: background-color .22s ease;
}
.pcs--warning::before {
  background: rgba(201, 48, 0, .12);
}

@media (max-width: 340px) {
  .pcs__form { max-width: 260px; }
  .pcs__input { font-size: 15px; padding-right: $sp-8; }
  .pcs__badgeText { font-size: 10px; }
}

@media (prefers-reduced-motion: reduce) {
  .pcs__badge {
    transition: none;
  }
  .pcs::before { transition: none; }
}

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);
}

.pcs {
  position: relative;
  width: min(92vw, 160vh - 12.8vw);
  aspect-ratio: 480/300;
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: center;
}

.pcs__form {
  width: 100%;
  max-width: 320px;
  box-sizing: border-box;
}

.pcs__field {
  display: grid;
  gap: 8px;
}

.pcs__labelRow {
  display: flex;
  align-items: center;
  gap: 8px;
  min-height: 26px;
}

.pcs__labelText {
  color: rgba(23, 20, 26, 0.82);
  font-weight: 600;
  font-size: 13px;
  line-height: 1.3;
}

.pcs__badge {
  display: inline-flex;
  align-items: center;
  gap: 4px;
  padding: 4px 8px;
  border-radius: 4px;
  background: #ffffff;
  color: #17141a;
  font-weight: 700;
  font-size: 11px;
  line-height: 1.4;
  opacity: 0;
  transform: translateY(14px) scale(0.86);
  transform-origin: left center;
  will-change: transform, opacity;
}

.pcs__badge--active {
  box-shadow: 0 6px 12px rgba(23, 20, 26, 0.32);
}

.pcs__badgeIcon {
  flex: 0 0 auto;
  color: #c93000;
}

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

.pcs__inputWrap {
  position: relative;
  display: flex;
  align-items: center;
}

.pcs__input {
  width: 100%;
  box-sizing: border-box;
  padding: 12px 40px 12px 16px;
  border-radius: 12px;
  border: 0;
  background: rgba(23, 20, 26, 0.06);
  color: #17141a;
  caret-color: #17141a;
  font-weight: 500;
  font-size: 17px;
  line-height: 1.3;
  letter-spacing: 0.06em;
}
.pcs__input:focus {
  outline: 2px solid #2f6df6;
  outline-offset: 2px;
}

.pcs__toggle {
  position: absolute;
  right: 8px;
  top: 50%;
  transform: translateY(-50%);
  width: 36px;
  height: 36px;
  display: grid;
  place-items: center;
  border: 0;
  border-radius: 999px;
  background: transparent;
  color: rgba(23, 20, 26, 0.78);
  cursor: pointer;
}
.pcs__toggle:hover {
  background: rgba(23, 20, 26, 0.08);
}
.pcs__toggle:focus-visible {
  outline: 2px solid #2f6df6;
  outline-offset: 2px;
}

.pcs__eyeHide {
  display: none;
}

.pcs--revealed .pcs__eyeShow {
  display: none;
}

.pcs--revealed .pcs__eyeHide {
  display: block;
}

.pcs::before {
  content: "";
  position: absolute;
  inset: 0;
  pointer-events: none;
  background: rgba(201, 48, 0, 0);
  transition: background-color 0.22s ease;
}

.pcs--warning::before {
  background: rgba(201, 48, 0, 0.12);
}

@media (max-width: 340px) {
  .pcs__form {
    max-width: 260px;
  }
  .pcs__input {
    font-size: 15px;
    padding-right: 32px;
  }
  .pcs__badgeText {
    font-size: 10px;
  }
}
@media (prefers-reduced-motion: reduce) {
  .pcs__badge {
    transition: none;
  }
  .pcs::before {
    transition: none;
  }
}

(function () {
  // 기법: keydown/keyup 에서 실제 KeyboardEvent.getModifierState('CapsLock') 을 읽어 setCapsLock() 하나로
  // 몰아 보낸다. 배지는 항상 DOM 에 있고 pos 스프링 값(0~1, 언더댐프라 1을 넘겨 튄다)으로 매 프레임
  // translateY·scale·opacity 를 다시 그린다. CAPSLOCK_BADGE_OVERSHOOT_PX 는 그 튐의 최대 폭(px).
  var root = document.getElementById('pcsRoot');
  var form = document.getElementById('pcsForm');
  var input = document.getElementById('pcsInput');
  var toggle = document.getElementById('pcsToggle');
  var badge = document.getElementById('pcsBadge');
  var announce = document.getElementById('pcsAnnounce');

  var CAPSLOCK_BADGE_OVERSHOOT_PX = 6;
  var SPRING_STIFFNESS = 210;
  var SPRING_DAMPING = 14;
  var BADGE_RISE_PX = 14;

  var LABEL_SHOW = 'Show password';
  var LABEL_HIDE = 'Hide password';
  var ANNOUNCE_ON = 'Caps Lock on';
  var ANNOUNCE_OFF = 'Caps Lock off';

  var reduce = window.matchMedia('(prefers-reduced-motion: reduce)').matches;

  function seedRand(seed) {
    var s = seed >>> 0;
    return function () { s = (s * 1664525 + 1013904223) >>> 0; return s / 4294967296; };
  }
  var pwRand = seedRand(426021);
  var POOL_ALL = 'ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnpqrstuvwxyz23456789!@#$%*?-';
  function makeFakePassword() {
    var len = 8 + Math.floor(pwRand() * 5);
    var out = '';
    for (var i = 0; i < len; i += 1) out += POOL_ALL.charAt(Math.floor(pwRand() * POOL_ALL.length));
    return out;
  }
  input.value = makeFakePassword();

  var revealed = false;
  function setRevealed(next) {
    revealed = next;
    input.type = revealed ? 'text' : 'password';
    toggle.setAttribute('aria-pressed', String(revealed));
    toggle.setAttribute('aria-label', revealed ? LABEL_HIDE : LABEL_SHOW);
    root.classList.toggle('pcs--revealed', revealed);
  }
  toggle.addEventListener('click', function () {
    root.classList.remove('is-demo');
    setRevealed(!revealed);
  });

  var pos = 0;
  var vel = 0;
  var target = 0;
  var springRaf = null;
  var lastT = null;

  function paintBadge(p) {
    var clamped = Math.min(1, Math.max(0, p));
    var overshoot = Math.max(0, p - 1);
    var y = BADGE_RISE_PX * (1 - clamped) - CAPSLOCK_BADGE_OVERSHOOT_PX * overshoot;
    var scale = 0.86 + 0.14 * clamped + 0.05 * overshoot;
    var opacity = Math.min(1, clamped * 3);
    badge.style.transform = 'translateY(' + y.toFixed(2) + 'px) scale(' + scale.toFixed(3) + ')';
    badge.style.opacity = String(opacity);
  }
  paintBadge(pos);

  function stepSpring(ts) {
    if (lastT === null) lastT = ts;
    var dt = Math.min(0.032, (ts - lastT) / 1000);
    lastT = ts;
    var acc = (target - pos) * SPRING_STIFFNESS - vel * SPRING_DAMPING;
    vel += acc * dt;
    pos += vel * dt;
    paintBadge(pos);
    var settled = Math.abs(target - pos) < 0.002 && Math.abs(vel) < 0.01;
    if (!settled) {
      springRaf = requestAnimationFrame(stepSpring);
    } else {
      pos = target;
      paintBadge(pos);
      springRaf = null;
      lastT = null;
    }
  }

  function setCapsLock(on) {
    var next = on ? 1 : 0;
    if (target === next) return;
    target = next;
    badge.classList.toggle('pcs__badge--active', on);
    root.classList.toggle('pcs--warning', on);
    announce.textContent = on ? ANNOUNCE_ON : ANNOUNCE_OFF;
    if (reduce) {
      if (springRaf) { cancelAnimationFrame(springRaf); springRaf = null; }
      pos = target;
      vel = 0;
      lastT = null;
      paintBadge(pos);
      return;
    }
    if (!springRaf) { lastT = null; springRaf = requestAnimationFrame(stepSpring); }
  }

  function onKey(e) {
    if (!e.getModifierState) return;
    setCapsLock(e.getModifierState('CapsLock'));
  }
  input.addEventListener('keydown', onKey);
  input.addEventListener('keyup', onKey);

  form.addEventListener('submit', function (e) { e.preventDefault(); });

  if (reduce) { root.classList.remove('is-demo'); }

  function demoLoop() {
    if (reduce) return;
    setCapsLock(true);
    setTimeout(function () { setCapsLock(false); }, 1100);
    setTimeout(demoLoop, 2200);
  }
  if (!reduce) { setTimeout(demoLoop, 240); }
})();

import { useEffect, useRef } from "react";
import styles from "./PasswordRevealCapslockWarningSpring.module.scss";

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

const CAPSLOCK_BADGE_OVERSHOOT_PX = 6;
const SPRING_STIFFNESS = 210;
const SPRING_DAMPING = 14;
const BADGE_RISE_PX = 14;
const LABEL_SHOW = "비밀번호 표시";
const LABEL_HIDE = "비밀번호 숨기기";
const ANNOUNCE_ON = "Caps Lock 켜짐";
const ANNOUNCE_OFF = "Caps Lock 꺼짐";

export default function PasswordRevealCapslockWarningSpring() {
  const rootRef = useRef(null) as unknown as Box<HTMLDivElement | null>;
  const formRef = useRef(null) as unknown as Box<HTMLFormElement | null>;
  const inputRef = useRef(null) as unknown as Box<HTMLInputElement | null>;
  const toggleRef = useRef(null) as unknown as Box<HTMLButtonElement | null>;
  const badgeRef = useRef(null) as unknown as Box<HTMLSpanElement | null>;
  const announceRef = useRef(null) as unknown as Box<HTMLSpanElement | null>;

  useEffect(() => {
    const root = rootRef.current;
    const form = formRef.current;
    const input = inputRef.current;
    const toggle = toggleRef.current;
    const badge = badgeRef.current;
    const announce = announceRef.current;
    if (!root || !form || !input || !toggle || !badge || !announce) return;

    const reduce = window.matchMedia("(prefers-reduced-motion: reduce)").matches;

    function seedRand(seed: number) {
      let s = seed >>> 0;
      return function () { s = (s * 1664525 + 1013904223) >>> 0; return s / 4294967296; };
    }
    const pwRand = seedRand(426022);
    const POOL_ALL = "ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnpqrstuvwxyz23456789!@#$%*?-";
    function makeFakePassword() {
      const len = 8 + Math.floor(pwRand() * 5);
      let out = "";
      for (let i = 0; i < len; i += 1) out += POOL_ALL.charAt(Math.floor(pwRand() * POOL_ALL.length));
      return out;
    }
    input.value = makeFakePassword();

    let revealed = false;
    function setRevealed(next: boolean) {
      revealed = next;
      input!.type = revealed ? "text" : "password";
      toggle!.setAttribute("aria-pressed", String(revealed));
      toggle!.setAttribute("aria-label", revealed ? LABEL_HIDE : LABEL_SHOW);
      root!.classList.toggle(styles["is-revealed"], revealed);
    }
    function onToggleClick() {
      root!.classList.remove(styles["is-demo"]);
      setRevealed(!revealed);
    }
    toggle.addEventListener("click", onToggleClick);

    let pos = 0;
    let vel = 0;
    let target = 0;
    let springRaf = 0;
    let lastT: number | null = null;

    function paintBadge(p: number) {
      const clamped = Math.min(1, Math.max(0, p));
      const overshoot = Math.max(0, p - 1);
      const y = BADGE_RISE_PX * (1 - clamped) - CAPSLOCK_BADGE_OVERSHOOT_PX * overshoot;
      const scale = 0.86 + 0.14 * clamped + 0.05 * overshoot;
      const opacity = Math.min(1, clamped * 3);
      badge!.style.transform = "translateY(" + y.toFixed(2) + "px) scale(" + scale.toFixed(3) + ")";
      badge!.style.opacity = String(opacity);
    }
    paintBadge(pos);

    function stepSpring(ts: number) {
      if (lastT === null) lastT = ts;
      const dt = Math.min(0.032, (ts - lastT) / 1000);
      lastT = ts;
      const acc = (target - pos) * SPRING_STIFFNESS - vel * SPRING_DAMPING;
      vel += acc * dt;
      pos += vel * dt;
      paintBadge(pos);
      const settled = Math.abs(target - pos) < 0.002 && Math.abs(vel) < 0.01;
      if (!settled) {
        springRaf = requestAnimationFrame(stepSpring);
      } else {
        pos = target;
        paintBadge(pos);
        springRaf = 0;
        lastT = null;
      }
    }

    function setCapsLock(on: boolean) {
      const next = on ? 1 : 0;
      if (target === next) return;
      target = next;
      badge!.classList.toggle(styles["badge--active"], on);
      root!.classList.toggle(styles.warning, on);
      announce!.textContent = on ? ANNOUNCE_ON : ANNOUNCE_OFF;
      if (reduce) {
        if (springRaf) { cancelAnimationFrame(springRaf); springRaf = 0; }
        pos = target;
        vel = 0;
        lastT = null;
        paintBadge(pos);
        return;
      }
      if (!springRaf) { lastT = null; springRaf = requestAnimationFrame(stepSpring); }
    }

    function onKey(e: KeyboardEvent) {
      if (!e.getModifierState) return;
      setCapsLock(e.getModifierState("CapsLock"));
    }
    input.addEventListener("keydown", onKey);
    input.addEventListener("keyup", onKey);

    function onSubmit(e: Event) { e.preventDefault(); }
    form.addEventListener("submit", onSubmit);

    if (reduce) { root.classList.remove(styles["is-demo"]); }

    let loopTimer = 0;
    let offTimer = 0;
    function demoLoop() {
      if (reduce) return;
      setCapsLock(true);
      offTimer = window.setTimeout(function () { setCapsLock(false); }, 1100);
      loopTimer = window.setTimeout(demoLoop, 2200);
    }
    let startTimer = 0;
    if (!reduce) { startTimer = window.setTimeout(demoLoop, 240); }

    return () => {
      toggle.removeEventListener("click", onToggleClick);
      input.removeEventListener("keydown", onKey);
      input.removeEventListener("keyup", onKey);
      form.removeEventListener("submit", onSubmit);
      if (springRaf) cancelAnimationFrame(springRaf);
      window.clearTimeout(startTimer);
      window.clearTimeout(loopTimer);
      window.clearTimeout(offTimer);
    };
  }, []);

  return (
    <main className={styles.stage}>
      <div ref={rootRef} className={`${styles.pcs} ${styles["is-demo"]}`}>
        <form ref={formRef} className={styles.form} noValidate>
          <label className={styles.field}>
            <span className={styles.labelRow}>
              <span className={styles.labelText}>비밀번호</span>
              <span ref={badgeRef} className={styles.badge} role="status">
                <svg className={styles.badgeIcon} width="1em" height="1em" viewBox="0 0 256 256" aria-hidden="true">
                  <g fill="currentColor">
                    <path d="M224 128a96 96 0 1 1-96-96a96 96 0 0 1 96 96" opacity=".2" />
                    <path d="M128 24a104 104 0 1 0 104 104A104.11 104.11 0 0 0 128 24m0 192a88 88 0 1 1 88-88a88.1 88.1 0 0 1-88 88m-8-80V80a8 8 0 0 1 16 0v56a8 8 0 0 1-16 0m20 36a12 12 0 1 1-12-12a12 12 0 0 1 12 12" />
                  </g>
                </svg>
                <span className={styles.badgeText}>Caps Lock</span>
              </span>
              <span ref={announceRef} className={styles.srAnnounce} aria-live="polite" />
            </span>
            <span className={styles.inputWrap}>
              <input
                ref={inputRef}
                className={styles.input}
                type="password"
                autoComplete="new-password"
                spellCheck={false}
                defaultValue=""
              />
              <button ref={toggleRef} className={styles.toggle} type="button" aria-pressed="false" aria-label="비밀번호 표시">
                <svg className={styles.eyeShow} viewBox="0 0 24 24" width={20} height={20} aria-hidden="true">
                  <path d="M2,12 C5,6 9,4 12,4 C15,4 19,6 22,12 C19,18 15,20 12,20 C9,20 5,18 2,12 Z" fill="none" stroke="currentColor" strokeWidth={2} />
                  <circle cx={12} cy={12} r={3.2} fill="currentColor" />
                </svg>
                <svg className={styles.eyeHide} viewBox="0 0 24 24" width={20} height={20} aria-hidden="true">
                  <path d="M2,12 Q12,4 22,12" fill="none" stroke="currentColor" strokeWidth={2} strokeLinecap="round" />
                  <path d="M2,12 Q12,20 22,12" fill="none" stroke="currentColor" strokeWidth={2} strokeLinecap="round" />
                </svg>
              </button>
            </span>
          </label>
        </form>
      </div>
    </main>
  );
}