01Confetti burst on button

<main class="stage">
  <div class="cb-wrap is-demo">
    <button class="cb-btn" type="button">Signed up</button>
    <span class="cb-piece"></span><span class="cb-piece"></span><span class="cb-piece"></span>
    <span class="cb-piece"></span><span class="cb-piece"></span><span class="cb-piece"></span>
    <span class="cb-piece"></span><span class="cb-piece"></span><span class="cb-piece"></span>
    <span class="cb-piece"></span><span class="cb-piece"></span><span class="cb-piece"></span>
  </div>
</main>

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

// ── 변수 3개 ──────────────────────────────────────────
$duration: 900ms;
$easing: $ease-pop;
$color: $subject-blue;

@include stage($stage-ink);

$piece-colors: $color, $stage-yellow, $stage-orange, $subject-cream;

.cb-wrap {
  position: relative;
  width: min(220px, 80vw);
  display: grid;
  place-items: center;
}

.cb-btn {
  position: relative;
  z-index: 1;
  border: 0;
  border-radius: $r-control;
  padding: $sp-3 $sp-6;
  background: $subject-blue-deep;
  color: $subject-cream;
  font: 700 14px/1 -apple-system, "Segoe UI", sans-serif;
  cursor: pointer;
}

.cb-piece {
  position: absolute;
  top: 50%;
  left: 50%;
  width: 9px;
  height: 9px;
  border-radius: $r-xs;
  opacity: 0;
  pointer-events: none;
}

// 조각마다 각도·거리·색·지연을 SCSS @for 로 흩뿌린다 — 마크업은 빈 span 12개뿐
@for $i from 1 through 12 {
  .cb-piece:nth-child(#{$i + 1}) {
    background: nth($piece-colors, ($i - 1) % 4 + 1);
    --angle: #{$i * 30deg};
    --dist: #{64px + ($i % 3) * 22px};
    animation-delay: #{($i % 4) * 40ms};
  }
}

@keyframes cb-fly {
  0%   { transform: translate(-50%, -50%) rotate(var(--angle)) translateY(0) scale(.4); opacity: 0; }
  15%  { opacity: 1; }
  100% { transform: translate(-50%, -50%) rotate(var(--angle)) translateY(calc(-1 * var(--dist))) scale(1); opacity: 0; }
}

// 실사용: 클릭이 is-burst 를 다시 붙여 keyframes 를 재생한다 (위 <script>)
.cb-wrap.is-burst .cb-piece,
.cb-wrap.is-demo .cb-piece { animation: cb-fly $duration $easing infinite; }

@media (prefers-reduced-motion: reduce) {
  .cb-wrap.is-burst .cb-piece,
  .cb-wrap.is-demo .cb-piece { animation: none !important; opacity: 0 !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);
}

.cb-wrap {
  position: relative;
  width: min(220px, 80vw);
  display: grid;
  place-items: center;
}

.cb-btn {
  position: relative;
  z-index: 1;
  border: 0;
  border-radius: 12px;
  padding: 12px 24px;
  background: #0a4fe8;
  color: #fff7e6;
  font: 700 14px/1 -apple-system, "Segoe UI", sans-serif;
  cursor: pointer;
}

.cb-piece {
  position: absolute;
  top: 50%;
  left: 50%;
  width: 9px;
  height: 9px;
  border-radius: 4px;
  opacity: 0;
  pointer-events: none;
}

.cb-piece:nth-child(2) {
  background: #2f6df6;
  --angle: 30deg;
  --dist: 86px;
  animation-delay: 40ms;
}

.cb-piece:nth-child(3) {
  background: #ffd23f;
  --angle: 60deg;
  --dist: 108px;
  animation-delay: 80ms;
}

.cb-piece:nth-child(4) {
  background: #ff4d1f;
  --angle: 90deg;
  --dist: 64px;
  animation-delay: 120ms;
}

.cb-piece:nth-child(5) {
  background: #fff7e6;
  --angle: 120deg;
  --dist: 86px;
  animation-delay: 0ms;
}

.cb-piece:nth-child(6) {
  background: #2f6df6;
  --angle: 150deg;
  --dist: 108px;
  animation-delay: 40ms;
}

.cb-piece:nth-child(7) {
  background: #ffd23f;
  --angle: 180deg;
  --dist: 64px;
  animation-delay: 80ms;
}

.cb-piece:nth-child(8) {
  background: #ff4d1f;
  --angle: 210deg;
  --dist: 86px;
  animation-delay: 120ms;
}

.cb-piece:nth-child(9) {
  background: #fff7e6;
  --angle: 240deg;
  --dist: 108px;
  animation-delay: 0ms;
}

.cb-piece:nth-child(10) {
  background: #2f6df6;
  --angle: 270deg;
  --dist: 64px;
  animation-delay: 40ms;
}

.cb-piece:nth-child(11) {
  background: #ffd23f;
  --angle: 300deg;
  --dist: 86px;
  animation-delay: 80ms;
}

.cb-piece:nth-child(12) {
  background: #ff4d1f;
  --angle: 330deg;
  --dist: 108px;
  animation-delay: 120ms;
}

.cb-piece:nth-child(13) {
  background: #fff7e6;
  --angle: 360deg;
  --dist: 64px;
  animation-delay: 0ms;
}

@keyframes cb-fly {
  0% {
    transform: translate(-50%, -50%) rotate(var(--angle)) translateY(0) scale(0.4);
    opacity: 0;
  }
  15% {
    opacity: 1;
  }
  100% {
    transform: translate(-50%, -50%) rotate(var(--angle)) translateY(calc(-1 * var(--dist))) scale(1);
    opacity: 0;
  }
}
.cb-wrap.is-burst .cb-piece,
.cb-wrap.is-demo .cb-piece {
  animation: cb-fly 900ms cubic-bezier(0.2, 1.4, 0.4, 1) infinite;
}

@media (prefers-reduced-motion: reduce) {
  .cb-wrap.is-burst .cb-piece,
  .cb-wrap.is-demo .cb-piece {
    animation: none !important;
    opacity: 0 !important;
  }
}

var wrap = document.querySelector('.cb-wrap');
var btn = document.querySelector('.cb-btn');
btn.addEventListener('click', function () {
  wrap.classList.remove('is-burst');
  void wrap.offsetWidth;
  wrap.classList.add('is-burst');
});

import { CSSProperties, useState } from "react";
import styles from "./ConfettiBurstButton.module.scss";

type Vars = CSSProperties & Record<string, string>;

export interface ConfettiBurstButtonProps {
  duration?: string;
  easing?: string;
  color?: string;
}

const COLORS = ["var(--color)", "#ffd23f", "#ff4d1f", "#fff7e6"];

// 실사용: 클릭마다 burstKey 를 올려 pieces 래퍼를 리마운트한다 — 같은 클래스를 다시 붙이는 것만으로는
// 이미 끝난 keyframes 가 재생되지 않는다 (바닐라판은 classList remove+reflow+add 로 같은 일을 한다)
export default function ConfettiBurstButton({
  duration = "900ms",
  easing = "cubic-bezier(.2, 1.4, .4, 1)",
  color = "#2f6df6",
}: ConfettiBurstButtonProps) {
  const [burstKey, setBurstKey] = useState(0);
  const style: Vars = { "--duration": duration, "--easing": easing, "--color": color };

  return (
    <div className={styles.wrap} style={style}>
      <button className={styles.btn} type="button" onClick={() => setBurstKey((k) => k + 1)}>
        가입 완료
      </button>
      <span key={burstKey} className={styles.pieces}>
        {Array.from({ length: 12 }, (_, i) => {
          const pieceStyle: Vars = {
            background: COLORS[i % COLORS.length],
            "--angle": `${(i + 1) * 30}deg`,
            "--dist": `${64 + (i % 3) * 22}px`,
            animationDelay: `${(i % 4) * 40}ms`,
          };
          return <span key={i} className={styles.piece} style={pieceStyle} />;
        })}
      </span>
    </div>
  );
}