07必須エラー振動切替 — 必須ボックスが空のまま送信を試みるとボックスの横位置の値が短く左右に揺れる方式

<main class="stage">
<div class="cbe is-demo" id="cbe">
  <label class="cbe__row" id="cbeRow">
    <input type="checkbox" class="cbe__input" id="cbeInput" required>
    <span class="cbe__box" id="cbeBox" aria-hidden="true">
      <svg viewBox="0 0 20 20" width="14" height="14"><path d="M4 10.5l3.5 3.5L16 5.5" fill="none" stroke="currentColor" stroke-width="2.6" stroke-linecap="round" stroke-linejoin="round"/></svg>
    </span>
    <span class="cbe__text">必須の利用規約に同意します</span>
  </label>
  <p class="cbe__hint" id="cbeHint">チェックしないと次に進めません</p>
  <button type="button" class="cbe__submit" id="cbeSubmit">送信</button>
</div>
</main>

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

// 계산 겹: index.html shakeOffset() 이 감쇠 사인 진동(exp(-ZETA·t)·sin(FREQ·t))을 직접 계산해
// translateX 값으로 삼는다 — 트윈 하나로 끝내지 않고 매 프레임 진폭이 줄어드는 물리량을 적분한다.
@include stage($stage-paper);

.cbe {
  display: grid;
  gap: $sp-3;
  width: 100%;
  max-width: 260px;
}

.cbe__row {
  display: flex;
  align-items: center;
  gap: $sp-3;
  padding: $sp-3;
  border-radius: $r-sm;
  border: 2px solid transparent;
  cursor: pointer;
  user-select: none;
  transition: border-color $dur-quick $ease-out, background-color $dur-quick $ease-out;
}

.cbe__row--error {
  border-color: $error;
  background: $error-soft;
}

.cbe__input {
  position: absolute;
  width: 1px;
  height: 1px;
  opacity: 0;
  pointer-events: none;
}

.cbe__box {
  flex: 0 0 auto;
  width: 22px;
  height: 22px;
  border-radius: $r-sm;
  border: 2px solid rgba($subject-ink, .32);
  color: $subject-cream;
  display: grid;
  place-items: center;
  box-sizing: border-box;
  transition: background-color $dur-quick $ease-out, border-color $dur-quick $ease-out;

  svg { opacity: 0; transition: opacity $dur-quick $ease-out; }
}

.cbe__input:checked + .cbe__box {
  background: $subject-blue;
  border-color: $subject-blue;

  svg { opacity: 1; }
}

.cbe__input:focus-visible + .cbe__box {
  outline: 2px solid $subject-blue-light;
  outline-offset: 2px;
}

.cbe__text {
  color: $subject-ink;
  font-size: 14px;
  font-weight: 600;
}

.cbe__hint {
  margin: 0;
  padding-left: $sp-3;
  color: rgba($subject-ink, .55);
  font-size: 12px;
  transition: color $dur-quick $ease-out, opacity $dur-quick $ease-out;
}

.cbe__hint--error {
  color: $error;
  opacity: 1;
}

.cbe__submit {
  justify-self: start;
  padding: $sp-2 $sp-5;
  border: none;
  border-radius: $r-sm;
  background: $subject-blue-deep;
  color: $subject-cream;
  font-size: 13px;
  font-weight: 700;
  cursor: pointer;
}

@media (max-width: 340px) {
  .cbe { max-width: 100%; }
  .cbe__text { font-size: 13px; }
}

@media (prefers-reduced-motion: reduce) {
  .cbe__row, .cbe__box, .cbe__box svg, .cbe__hint { transition: none; }
}

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

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

.cbe {
  display: grid;
  gap: 12px;
  width: 100%;
  max-width: 260px;
}

.cbe__row {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 12px;
  border-radius: 8px;
  border: 2px solid transparent;
  cursor: pointer;
  user-select: none;
  transition: border-color 220ms ease-out, background-color 220ms ease-out;
}

.cbe__row--error {
  border-color: #c2361a;
  background: #ffe0d8;
}

.cbe__input {
  position: absolute;
  width: 1px;
  height: 1px;
  opacity: 0;
  pointer-events: none;
}

.cbe__box {
  flex: 0 0 auto;
  width: 22px;
  height: 22px;
  border-radius: 8px;
  border: 2px solid rgba(23, 20, 26, 0.32);
  color: #fff7e6;
  display: grid;
  place-items: center;
  box-sizing: border-box;
  transition: background-color 220ms ease-out, border-color 220ms ease-out;
}
.cbe__box svg {
  opacity: 0;
  transition: opacity 220ms ease-out;
}

.cbe__input:checked + .cbe__box {
  background: #2f6df6;
  border-color: #2f6df6;
}
.cbe__input:checked + .cbe__box svg {
  opacity: 1;
}

.cbe__input:focus-visible + .cbe__box {
  outline: 2px solid #5b8cf8;
  outline-offset: 2px;
}

.cbe__text {
  color: #17141a;
  font-size: 14px;
  font-weight: 600;
}

.cbe__hint {
  margin: 0;
  padding-left: 12px;
  color: rgba(23, 20, 26, 0.55);
  font-size: 12px;
  transition: color 220ms ease-out, opacity 220ms ease-out;
}

.cbe__hint--error {
  color: #c2361a;
  opacity: 1;
}

.cbe__submit {
  justify-self: start;
  padding: 8px 20px;
  border: none;
  border-radius: 8px;
  background: #0a4fe8;
  color: #fff7e6;
  font-size: 13px;
  font-weight: 700;
  cursor: pointer;
}

@media (max-width: 340px) {
  .cbe {
    max-width: 100%;
  }
  .cbe__text {
    font-size: 13px;
  }
}
@media (prefers-reduced-motion: reduce) {
  .cbe__row, .cbe__box, .cbe__box svg, .cbe__hint {
    transition: none;
  }
}

(function () {
  var SHAKE_MS = 420; // 계산 겹 상수: 흔들림 감쇠가 끝나는 데 걸리는 실제 시간(ms)
  var SHAKE_FREQ = 2 * Math.PI * 5 / SHAKE_MS; // 흔들림 진동 주파수
  var SHAKE_ZETA = 4.2; // 감쇠 계수
  var SHAKE_AMP = 8; // px, 최대 흔들림 폭
  var CYCLE_MS = 480;
  var reduce = window.matchMedia('(prefers-reduced-motion: reduce)').matches;

  var root = document.getElementById('cbe');
  var input = document.getElementById('cbeInput');
  var box = document.getElementById('cbeBox');
  var row = document.getElementById('cbeRow');
  var hint = document.getElementById('cbeHint');
  var submit = document.getElementById('cbeSubmit');

  var isDemo = true;
  var shaking = false, shakeStart = 0;

  function human() {
    if (isDemo) { root.classList.remove('is-demo'); isDemo = false; }
  }

  function shakeOffset(t) {
    // 계산 겹: 감쇠 사인 진동 — 시간이 지날수록 진폭이 줄어드는 흔들림 값을 직접 계산
    var amp = Math.exp(-SHAKE_ZETA * (t / SHAKE_MS));
    return SHAKE_AMP * amp * Math.sin(SHAKE_FREQ * t);
  }

  function triggerError() {
    row.classList.add('cbe__row--error');
    hint.classList.add('cbe__hint--error');
    shakeStart = performance.now();
    shaking = true;
  }

  function clearError() {
    row.classList.remove('cbe__row--error');
    hint.classList.remove('cbe__hint--error');
  }

  input.addEventListener('change', function () {
    human();
    if (input.checked) clearError();
  });

  submit.addEventListener('click', function () {
    human();
    if (!input.checked) { triggerError(); } else { clearError(); }
  });

  var cycleStart = 0;
  var lastStep = -1;

  function loop(ts) {
    if (!cycleStart) cycleStart = ts;

    if (isDemo) {
      var step = Math.floor((ts - cycleStart) / CYCLE_MS) % 3;
      if (step !== lastStep) {
        lastStep = step;
        if (step === 0) { input.checked = false; clearError(); }
        else if (step === 1) { triggerError(); }
        else { input.checked = true; clearError(); }
      }
    }

    if (shaking) {
      var t = ts - shakeStart;
      if (t >= SHAKE_MS) {
        shaking = false;
        row.style.transform = '';
      } else {
        row.style.transform = 'translateX(' + shakeOffset(t).toFixed(2) + 'px)';
      }
    }

    requestAnimationFrame(loop);
  }

  if (reduce) { SHAKE_MS = 1; }
  requestAnimationFrame(loop);
})();

// ErrorShakeRequired — vanilla 판(run/368/demo/07-custom-checkbox-error-shake-required/index.html)
// 의 React 포트. 감쇠 사인 진동(exp(-SHAKE_ZETA·t)·sin(SHAKE_FREQ·t))을 직접 계산해 translateX
// 값으로 삼는다 — 트윈 하나로 끝내지 않고 매 프레임 진폭이 줄어드는 물리량을 적분한다.
import { useEffect, useRef } from "react";
import styles from "./ErrorShakeRequired.module.scss";

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

export default function ErrorShakeRequired() {
  const rootRef = useRef(null) as unknown as Box<HTMLDivElement>;
  const inputRef = useRef(null) as unknown as Box<HTMLInputElement>;
  const rowRef = useRef(null) as unknown as Box<HTMLLabelElement>;
  const hintRef = useRef(null) as unknown as Box<HTMLParagraphElement>;
  const submitRef = useRef(null) as unknown as Box<HTMLButtonElement>;
  const rafRef = useRef(0) as unknown as Box<number>;

  useEffect(() => {
    let SHAKE_MS = 420; // 계산 겹 상수: 흔들림 감쇠가 끝나는 데 걸리는 실제 시간(ms)
    const SHAKE_FREQ = (2 * Math.PI * 5) / SHAKE_MS; // 흔들림 진동 주파수
    const SHAKE_ZETA = 4.2; // 감쇠 계수
    const SHAKE_AMP = 8; // px, 최대 흔들림 폭
    const CYCLE_MS = 480;
    const reduce = window.matchMedia("(prefers-reduced-motion: reduce)").matches;

    const root = rootRef.current;
    const input = inputRef.current;
    const row = rowRef.current;
    const hint = hintRef.current;
    const submit = submitRef.current;
    if (!root || !input || !row || !hint || !submit) return;

    let isDemo = true;
    let shaking = false, shakeStart = 0;

    function human() {
      if (isDemo) { root!.classList.remove(styles.isDemo); isDemo = false; }
    }

    function shakeOffset(t: number) {
      // 계산 겹: 감쇠 사인 진동 — 시간이 지날수록 진폭이 줄어드는 흔들림 값을 직접 계산
      const amp = Math.exp(-SHAKE_ZETA * (t / SHAKE_MS));
      return SHAKE_AMP * amp * Math.sin(SHAKE_FREQ * t);
    }

    function triggerError() {
      row!.classList.add(styles.rowError);
      hint!.classList.add(styles.hintError);
      shakeStart = performance.now();
      shaking = true;
    }

    function clearError() {
      row!.classList.remove(styles.rowError);
      hint!.classList.remove(styles.hintError);
    }

    function onInputChange() { human(); if (input!.checked) clearError(); }
    input.addEventListener("change", onInputChange);

    function onSubmitClick() {
      human();
      if (!input!.checked) { triggerError(); } else { clearError(); }
    }
    submit.addEventListener("click", onSubmitClick);

    let cycleStart = 0;
    let lastStep = -1;

    function loop(ts: number) {
      if (!cycleStart) cycleStart = ts;

      if (isDemo) {
        const step = Math.floor((ts - cycleStart) / CYCLE_MS) % 3;
        if (step !== lastStep) {
          lastStep = step;
          if (step === 0) { input!.checked = false; clearError(); }
          else if (step === 1) { triggerError(); }
          else { input!.checked = true; clearError(); }
        }
      }

      if (shaking) {
        const t = ts - shakeStart;
        if (t >= SHAKE_MS) {
          shaking = false;
          row!.style.transform = "";
        } else {
          row!.style.transform = "translateX(" + shakeOffset(t).toFixed(2) + "px)";
        }
      }

      rafRef.current = requestAnimationFrame(loop);
    }

    if (reduce) { SHAKE_MS = 1; }
    rafRef.current = requestAnimationFrame(loop);

    return () => {
      input.removeEventListener("change", onInputChange);
      submit.removeEventListener("click", onSubmitClick);
      cancelAnimationFrame(rafRef.current);
    };
  }, []);

  return (
    <main className={styles.stage}>
      <div className={styles.cbe + " " + styles.isDemo} ref={rootRef}>
        <label className={styles.cbeRow} ref={rowRef}>
          <input type="checkbox" className={styles.cbeInput} ref={inputRef} required />
          <span className={styles.cbeBox} aria-hidden="true">
            <svg viewBox="0 0 20 20" width={14} height={14}>
              <path d="M4 10.5l3.5 3.5L16 5.5" fill="none" stroke="currentColor" strokeWidth={2.6} strokeLinecap="round" strokeLinejoin="round" />
            </svg>
          </span>
          <span className={styles.cbeText}>필수 약관에 동의합니다</span>
        </label>
        <p className={styles.cbeHint} ref={hintRef}>체크해야 다음으로 진행됩니다</p>
        <button type="button" className={styles.cbeSubmit} ref={submitRef}>제출</button>
      </div>
    </main>
  );
}