04Testimonial carousel — a card track whose auto-advance value grows on a timer

<main class="stage" id="stage">
  <div class="carousel" id="carousel">
    <div class="track is-demo" id="track">
      <blockquote class="t-card">
        <p class="t-card__quote">Installation was really easy</p>
        <p class="t-card__name">Minji Kim</p>
      </blockquote>
      <blockquote class="t-card">
        <p class="t-card__quote">Customer support is fast</p>
        <p class="t-card__name">Seojun Park</p>
      </blockquote>
      <blockquote class="t-card">
        <p class="t-card__quote">The design is clean</p>
        <p class="t-card__name">Haneul Lee</p>
      </blockquote>
    </div>
  </div>
</main>

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

$duration: $dur-loop;
$easing: $ease-spring;
$color: $subject-blue-deep;

@include stage($stage-paper);

.carousel {
  width: 100%;
  max-width: 320px;
  overflow: hidden;
  border-radius: $r-card;
}

.track {
  display: flex;
  width: 100%;
}

.t-card {
  box-sizing: border-box;
  flex: 0 0 100%;
  margin: 0;
  padding: $sp-6 $sp-4;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: $sp-2;
  background: $color;
  text-align: center;
}

.t-card__quote {
  margin: 0;
  color: $stage-paper;
  font-weight: 600;
  font-size: 13px;
  line-height: 1.5;
}

.t-card__quote::before { content: "\201C"; }
.t-card__quote::after { content: "\201D"; }

.t-card__name {
  margin: 0;
  color: rgba($stage-paper, .78);
  font-weight: 400;
  font-size: 11px;
  line-height: 1.5;
}

.track.is-demo {
  animation: advance $duration $easing infinite;
}

@keyframes advance {
  0%, 20% { transform: translateX(0); }
  33%, 63% { transform: translateX(-100%); }
  76%, 96% { transform: translateX(-200%); }
  100% { transform: translateX(0); }
}

@media (max-width: 340px) {
  .carousel { max-width: 240px; }
  .t-card { padding: $sp-4 $sp-3; }
}

@media (prefers-reduced-motion: reduce) {
  .track.is-demo { animation: none; transform: none; }
}

@charset "UTF-8";
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);
}

.carousel {
  width: 100%;
  max-width: 320px;
  overflow: hidden;
  border-radius: 16px;
}

.track {
  display: flex;
  width: 100%;
}

.t-card {
  box-sizing: border-box;
  flex: 0 0 100%;
  margin: 0;
  padding: 24px 16px;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 8px;
  background: #0a4fe8;
  text-align: center;
}

.t-card__quote {
  margin: 0;
  color: #ffffff;
  font-weight: 600;
  font-size: 13px;
  line-height: 1.5;
}

.t-card__quote::before {
  content: "“";
}

.t-card__quote::after {
  content: "”";
}

.t-card__name {
  margin: 0;
  color: rgba(255, 255, 255, 0.78);
  font-weight: 400;
  font-size: 11px;
  line-height: 1.5;
}

.track.is-demo {
  animation: advance 2s cubic-bezier(0.2, 0.8, 0.2, 1) infinite;
}

@keyframes advance {
  0%, 20% {
    transform: translateX(0);
  }
  33%, 63% {
    transform: translateX(-100%);
  }
  76%, 96% {
    transform: translateX(-200%);
  }
  100% {
    transform: translateX(0);
  }
}
@media (max-width: 340px) {
  .carousel {
    max-width: 240px;
  }
  .t-card {
    padding: 16px 12px;
  }
}
@media (prefers-reduced-motion: reduce) {
  .track.is-demo {
    animation: none;
    transform: none;
  }
}

// 자동 진행 값이 타이머로 계속 늘어나며 카드 위치를 다음 카드로 보간한다. 포인터가 올라와 있는 동안은 그 값이 늘지 않는다.
// 계산 겹: 자동 진행 값(interval) -> translateX 보간. 실사용 포인터 리스너 있음(데모 재생 자체는 고정 시퀀스).
(function () {
  var carousel = document.getElementById('carousel');
  var track = document.getElementById('track');
  if (!carousel || !track) return;

  var count = track.children.length;
  var index = 0;
  var timer = null;
  var live = false;

  function render() {
    track.style.transform = 'translateX(' + (index * -100) + '%)';
  }

  function advance() {
    index = (index + 1) % count;
    render();
  }

  function stop() {
    if (timer !== null) { window.clearInterval(timer); timer = null; }
  }

  function start() {
    stop();
    timer = window.setInterval(advance, 2600);
  }

  function goLive() {
    if (live) return;
    live = true;
    track.classList.remove('is-demo');
    render();
    start();
  }

  carousel.addEventListener('pointerenter', function () {
    goLive();
    stop();
  });

  carousel.addEventListener('pointerleave', function () {
    if (live) start();
  });
})();

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

// 자동 진행 값이 타이머로 계속 늘어나며 카드 위치를 다음 카드로 보간한다. 포인터가 올라와 있는 동안은 그 값이 늘지 않는다.
// 계산 겹: 자동 진행 값(interval) -> translateX 보간. 실사용 포인터 리스너 있음(데모 재생 자체는 고정 시퀀스).
const REVIEWS = [
  { quote: "설치가 정말 쉬웠어요", name: "김민지" },
  { quote: "고객 지원이 빨라요", name: "박서준" },
  { quote: "디자인이 깔끔해요", name: "이하늘" },
];

export default function TestimonialCarousel() {
  const carouselRef = useRef<HTMLDivElement>(null);
  const trackRef = useRef<HTMLDivElement>(null);

  useEffect(() => {
    const carousel = carouselRef.current;
    const track = trackRef.current;
    if (!carousel || !track) return;

    const count = track.children.length;
    let index = 0;
    let timer: number | null = null;
    let live = false;

    function render() {
      track!.style.transform = "translateX(" + index * -100 + "%)";
    }

    function advance() {
      index = (index + 1) % count;
      render();
    }

    function stop() {
      if (timer !== null) {
        window.clearInterval(timer);
        timer = null;
      }
    }

    function start() {
      stop();
      timer = window.setInterval(advance, 2600);
    }

    function goLive() {
      if (live) return;
      live = true;
      track!.classList.remove(styles["is-demo"]);
      render();
      start();
    }

    function onEnter() {
      goLive();
      stop();
    }

    function onLeave() {
      if (live) start();
    }

    carousel.addEventListener("pointerenter", onEnter);
    carousel.addEventListener("pointerleave", onLeave);
    return () => {
      stop();
      carousel.removeEventListener("pointerenter", onEnter);
      carousel.removeEventListener("pointerleave", onLeave);
    };
  }, []);

  return (
    <main className={styles.stage}>
      <div ref={carouselRef} className={styles.carousel}>
        <div ref={trackRef} className={`${styles.track} ${styles["is-demo"]}`}>
          {REVIEWS.map((r) => (
            <blockquote key={r.name} className={styles["t-card"]}>
              <p className={styles["t-card__quote"]}>{r.quote}</p>
              <p className={styles["t-card__name"]}>{r.name}</p>
            </blockquote>
          ))}
        </div>
      </div>
    </main>
  );
}