07:user-invalidで自動的に揺れる

<main class="stage">
  <div class="ui is-demo">
    <label class="ui__label" for="ui-email">メール</label>
    <input class="ui__input" id="ui-email" type="email" required pattern=".+@.+\..+" value="broken">
    <p class="ui__msg">正しいメールアドレスを入力してください</p>
  </div>
</main>

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

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

@include stage($stage-orange);

.ui { width: min(260px, 86vw); display: flex; flex-direction: column; gap: $sp-2; }
.ui__label { font-weight: 600; font-size: 12px; line-height: 1; font-family: inherit; color: $subject-ink; }
.ui__input {
  box-sizing: border-box;
  width: 100%;
  padding: $sp-2 $sp-3;
  border-radius: $r-sm;
  border: 2px solid rgba(23, 20, 26, .2);
  background: #fff;
  color: $subject-ink;
  font-weight: 400;
  font-size: 14px;
  line-height: 1;
  font-family: inherit;
}
.ui__msg { margin: 0; color: $subject-ink; font-weight: 500; font-size: 11px; line-height: 1.3; font-family: inherit; }

@keyframes ui-shake {
  0%, 22%, 100% { transform: translateX(0); }
  2%  { transform: translateX(-7px); }
  4%  { transform: translateX(7px); }
  6%  { transform: translateX(-7px); }
  8%  { transform: translateX(7px); }
  10% { transform: translateX(-5px); }
  12% { transform: translateX(5px); }
  14% { transform: translateX(-3px); }
  16% { transform: translateX(3px); }
}
// 실제 동작: JS 없이 :user-invalid 만으로 흔들린다. 값을 만지고 벗어난 뒤에만 켜진다
.ui__input:user-invalid { border-color: $color; animation: ui-shake $duration $easing; }

// 데모 루프: :user-invalid 활성화 타이밍이 브라우저마다 달라 .is-demo 로 강제한다
.ui.is-demo .ui__input { animation: ui-shake $duration $easing infinite; }

@media (prefers-reduced-motion: reduce) {
  .ui__input:user-invalid,
  .ui.is-demo .ui__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: #ff4d1f;
  font-family: -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  padding: clamp(8px, 4vw, 24px);
}

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

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

.ui__input {
  box-sizing: border-box;
  width: 100%;
  padding: 8px 12px;
  border-radius: 8px;
  border: 2px solid rgba(23, 20, 26, 0.2);
  background: #fff;
  color: #17141a;
  font-weight: 400;
  font-size: 14px;
  line-height: 1;
  font-family: inherit;
}

.ui__msg {
  margin: 0;
  color: #17141a;
  font-weight: 500;
  font-size: 11px;
  line-height: 1.3;
  font-family: inherit;
}

@keyframes ui-shake {
  0%, 22%, 100% {
    transform: translateX(0);
  }
  2% {
    transform: translateX(-7px);
  }
  4% {
    transform: translateX(7px);
  }
  6% {
    transform: translateX(-7px);
  }
  8% {
    transform: translateX(7px);
  }
  10% {
    transform: translateX(-5px);
  }
  12% {
    transform: translateX(5px);
  }
  14% {
    transform: translateX(-3px);
  }
  16% {
    transform: translateX(3px);
  }
}
.ui__input:user-invalid {
  border-color: #c2361a;
  animation: ui-shake 500ms ease-out;
}

.ui.is-demo .ui__input {
  animation: ui-shake 500ms ease-out infinite;
}

@media (prefers-reduced-motion: reduce) {
  .ui__input:user-invalid,
  .ui.is-demo .ui__input {
    animation: none !important;
  }
}

// CSS 만으로는 :user-invalid 가 "사용자가 값을 만지고 벗어난 뒤" 에만 켜진다.
// 데모에서 그 상태를 보여주려고 포커스·입력·블러를 흉내만 낸다 (JS 4줄).
var el = document.getElementById('ui-email');
el.focus({ preventScroll: true });
el.dispatchEvent(new Event('input'));
el.blur();

import { useState } from "react";
import type { CSSProperties, ChangeEvent } from "react";
import styles from "./UserInvalidShake.module.scss";

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

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

// React 는 :user-invalid 를 직접 읽지 못해, onBlur 에서 checkValidity() 로 같은 순간을 흉내 낸다.
// 실제 zip 의 vanilla 판은 JS 없이 CSS 의사 클래스 하나로 끝난다 — 이 파일은 React 이식일 뿐이다.
export default function UserInvalidShake({ duration = 500, easing = "ease-out", color = "#c2361a" }: UserInvalidShakeProps) {
  const [touched, setTouched] = useState(true);
  const [run, setRun] = useState(0);
  const vars: Vars = { "--duration": `${duration}ms`, "--easing": easing, "--color": color };

  const onBlur = (e: ChangeEvent<HTMLInputElement>) => {
    setTouched(!e.target.checkValidity());
    setRun((n) => n + 1);
  };

  return (
    <div className={styles.ui} style={vars}>
      <label className={styles.label} htmlFor="ui-email">이메일</label>
      <input
        key={run}
        id="ui-email"
        className={`${styles.input} ${touched ? styles.shake : ""}`}
        type="email"
        required
        pattern=".+@.+\..+"
        defaultValue="broken"
        onBlur={onBlur}
      />
      <p className={styles.msg}>올바른 이메일 주소를 입력하세요</p>
    </div>
  );
}