081回再生のリセットパターン

<main class="stage">
  <div class="rs is-demo">
    <label class="rs__label" for="rs-pw">パスワード</label>
    <input class="rs__input" id="rs-pw" type="password" value="wrong1" readonly>
    <button class="rs__btn" type="button" id="rs-check">再確認</button>
    <p class="rs__msg">パスワードが違います</p>
  </div>
</main>

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

$duration: 500ms;                                 // 흔들림 한 번의 길이
$easing: $ease-out;
$color: $error;

@include stage($stage-paper);

.rs { width: min(260px, 86vw); display: flex; flex-direction: column; gap: $sp-2; }
.rs__label { font-weight: 600; font-size: 12px; line-height: 1; font-family: inherit; color: $subject-ink; }
.rs__input {
  box-sizing: border-box;
  width: 100%;
  padding: $sp-2 $sp-3;
  border-radius: $r-sm;
  border: 2px solid $color;
  background: #fff;
  color: $subject-ink;
  font-weight: 400;
  font-size: 14px;
  line-height: 1;
  font-family: inherit;
}
.rs__btn {
  align-self: flex-start;
  padding: $sp-1 $sp-3;
  border: 1px solid rgba(23, 20, 26, .3);
  border-radius: $r-control;
  background: none;
  color: $subject-ink;
  font-weight: 600;
  font-size: 12px;
  line-height: 1;
  font-family: inherit;
}
.rs__msg { margin: 0; color: $color; font-weight: 500; font-size: 11px; line-height: 1.3; font-family: inherit; }

@keyframes rs-shake {
  0%, 100% { transform: translateX(0); }
  10% { transform: translateX(-7px); }
  20% { transform: translateX(6px); }
  30% { transform: translateX(-5px); }
  40% { transform: translateX(4px); }
  50% { transform: translateX(-3px); }
  60% { transform: translateX(2px); }
  70% { transform: translateX(-1px); }
  80% { transform: translateX(1px); }
}
// 실제 동작: "다시 확인" 을 연속으로 눌러도 리플로우 트릭 덕분에 매번 새로 흔들린다
.rs__input.rs--shake { animation: rs-shake $duration $easing; }

// 데모 루프: 같은 흔들림을 반복해 "매번 처음부터" 를 보여준다
.rs.is-demo .rs__input { animation: rs-shake $duration $easing infinite; }

@media (prefers-reduced-motion: reduce) {
  .rs__input.rs--shake,
  .rs.is-demo .rs__input { animation: none !important; }
}

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);
}

.rs {
  width: min(260px, 86vw);
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.rs__label {
  font-weight: 600;
  font-size: 12px;
  line-height: 1;
  font-family: inherit;
  color: #17141a;
}

.rs__input {
  box-sizing: border-box;
  width: 100%;
  padding: 8px 12px;
  border-radius: 8px;
  border: 2px solid #c2361a;
  background: #fff;
  color: #17141a;
  font-weight: 400;
  font-size: 14px;
  line-height: 1;
  font-family: inherit;
}

.rs__btn {
  align-self: flex-start;
  padding: 4px 12px;
  border: 1px solid rgba(23, 20, 26, 0.3);
  border-radius: 12px;
  background: none;
  color: #17141a;
  font-weight: 600;
  font-size: 12px;
  line-height: 1;
  font-family: inherit;
}

.rs__msg {
  margin: 0;
  color: #c2361a;
  font-weight: 500;
  font-size: 11px;
  line-height: 1.3;
  font-family: inherit;
}

@keyframes rs-shake {
  0%, 100% {
    transform: translateX(0);
  }
  10% {
    transform: translateX(-7px);
  }
  20% {
    transform: translateX(6px);
  }
  30% {
    transform: translateX(-5px);
  }
  40% {
    transform: translateX(4px);
  }
  50% {
    transform: translateX(-3px);
  }
  60% {
    transform: translateX(2px);
  }
  70% {
    transform: translateX(-1px);
  }
  80% {
    transform: translateX(1px);
  }
}
.rs__input.rs--shake {
  animation: rs-shake 500ms ease-out;
}

.rs.is-demo .rs__input {
  animation: rs-shake 500ms ease-out infinite;
}

@media (prefers-reduced-motion: reduce) {
  .rs__input.rs--shake,
  .rs.is-demo .rs__input {
    animation: none !important;
  }
}

// 같은 클래스를 다시 붙이기만 하면 애니메이션이 재생되지 않는다.
// 지우고 → 강제 리플로우(offsetWidth) → 다시 붙이면 매번 처음부터 흔들린다 (JS 6줄).
var input = document.getElementById('rs-pw');
document.getElementById('rs-check').addEventListener('pointerdown', function () {
  input.classList.remove('rs--shake');
  void input.offsetWidth;
  input.classList.add('rs--shake');
});

import { useState } from "react";
import type { CSSProperties } from "react";
import styles from "./ShakeOnceReset.module.scss";

export type ShakeOnceResetProps = {
  duration?: number;
  easing?: string;
  color?: string;
};

type Vars = CSSProperties & { "--duration"?: string; "--easing"?: string; "--color"?: string };

// DOM 판의 리플로우 트릭 대신, React 는 key 를 바꿔 요소를 통째로 새로 마운트한다 —
// 같은 효과(매번 처음부터 재생)를 React 답게 낸다.
export default function ShakeOnceReset({ duration = 500, easing = "ease-out", color = "#c2361a" }: ShakeOnceResetProps) {
  const [run, setRun] = useState(0);
  const vars: Vars = { "--duration": `${duration}ms`, "--easing": easing, "--color": color };

  return (
    <div className={styles.rs} style={vars}>
      <label className={styles.label} htmlFor="rs-pw">비밀번호</label>
      <input key={run} id="rs-pw" className={`${styles.input} ${styles.shake}`} type="password" defaultValue="wrong1" readOnly />
      <button type="button" className={styles.btn} onClick={() => setRun((n) => n + 1)}>다시 확인</button>
      <p className={styles.msg}>비밀번호가 틀렸습니다</p>
    </div>
  );
}