07Live currency format — a stepper that recomputes digit-grouping positions every time its value changes

<main class="stage">
<div class="nspcf is-demo" id="nspcf">
  <div class="nspcf__panel">
    <span class="nspcf__label">Coin balance</span>
    <div class="nspcf__amount">
      <span class="nspcf__symbol">◆</span>
      <span class="nspcf__col" data-col="0"><span class="nspcf__digit nspcf__digit--old">0</span><span class="nspcf__digit nspcf__digit--new">0</span></span>
      <span class="nspcf__comma">,</span>
      <span class="nspcf__col" data-col="1"><span class="nspcf__digit nspcf__digit--old">0</span><span class="nspcf__digit nspcf__digit--new">0</span></span>
      <span class="nspcf__col" data-col="2"><span class="nspcf__digit nspcf__digit--old">0</span><span class="nspcf__digit nspcf__digit--new">0</span></span>
      <span class="nspcf__col" data-col="3"><span class="nspcf__digit nspcf__digit--old">0</span><span class="nspcf__digit nspcf__digit--new">0</span></span>
    </div>
    <div class="nspcf__row">
      <button class="nspcf__btn" id="nspcfMinus" aria-label="Decrease by 250" type="button">−</button>
      <button class="nspcf__btn" id="nspcfPlus" aria-label="Increase by 250" type="button">+</button>
    </div>
  </div>
</div>
</main>

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

// 계산 겹: 자릿수(place)가 클수록 굴러가는 시작을 늦추고(delay) 더 오래 돈다(duration) —
// 1의 자리가 먼저 넘어가고 그 여파가 왼쪽 자리로 번지는 기계식 계기판 캐스케이드.

$duration: $dur-quick;
$easing: $ease-out;
$color: $subject-blue-deep;

@include stage($stage-orange);

.stage { position: relative; }

.nspcf {
  width: min(240px, 70vw);
}

.nspcf__panel {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: $sp-4;
  padding: $sp-5;
  border-radius: $r-card;
  background: $stage-paper;
}

.nspcf__label {
  color: rgba($subject-ink, .72);
  font-weight: 700;
  font-size: 12px;
}

.nspcf__amount {
  display: flex;
  align-items: center;
  gap: $sp-1;
}

.nspcf__symbol {
  color: $color;
  font-weight: 700;
  font-size: 22px;
  margin-right: $sp-1;
}

.nspcf__col {
  position: relative;
  display: inline-block;
  width: 18px;
  height: 32px;
  overflow: hidden;
}

.nspcf__digit {
  position: absolute;
  inset: 0;
  display: grid;
  place-items: center;
  color: $subject-ink;
  font-weight: 700;
  font-size: 26px;
  font-variant-numeric: tabular-nums;
  will-change: transform;
}

.nspcf__comma {
  color: $subject-ink;
  font-weight: 700;
  font-size: 22px;
  transform: translateY(6px);
}

.nspcf__row {
  display: flex;
  gap: $sp-3;
}

.nspcf__btn {
  width: 36px;
  height: 36px;
  border: 0;
  border-radius: $r-pill;
  background: $color;
  color: $subject-cream;
  font-size: 18px;
  font-weight: 700;
  line-height: 1;
  cursor: pointer;

  &:active { transform: scale(.92); }
}

@media (max-width: 340px) {
  .nspcf__panel { padding: $sp-4; gap: $sp-3; }
  .nspcf__symbol { font-size: 18px; }
  .nspcf__digit { font-size: 22px; }
  .nspcf__col { width: 15px; height: 28px; }
  .nspcf__btn { width: 32px; height: 32px; }
}

@media (prefers-reduced-motion: reduce) {
  .nspcf__digit { transition: 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);
}

.stage {
  position: relative;
}

.nspcf {
  width: min(240px, 70vw);
}

.nspcf__panel {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 16px;
  padding: 20px;
  border-radius: 16px;
  background: #ffffff;
}

.nspcf__label {
  color: rgba(23, 20, 26, 0.72);
  font-weight: 700;
  font-size: 12px;
}

.nspcf__amount {
  display: flex;
  align-items: center;
  gap: 4px;
}

.nspcf__symbol {
  color: #0a4fe8;
  font-weight: 700;
  font-size: 22px;
  margin-right: 4px;
}

.nspcf__col {
  position: relative;
  display: inline-block;
  width: 18px;
  height: 32px;
  overflow: hidden;
}

.nspcf__digit {
  position: absolute;
  inset: 0;
  display: grid;
  place-items: center;
  color: #17141a;
  font-weight: 700;
  font-size: 26px;
  font-variant-numeric: tabular-nums;
  will-change: transform;
}

.nspcf__comma {
  color: #17141a;
  font-weight: 700;
  font-size: 22px;
  transform: translateY(6px);
}

.nspcf__row {
  display: flex;
  gap: 12px;
}

.nspcf__btn {
  width: 36px;
  height: 36px;
  border: 0;
  border-radius: 999px;
  background: #0a4fe8;
  color: #fff7e6;
  font-size: 18px;
  font-weight: 700;
  line-height: 1;
  cursor: pointer;
}
.nspcf__btn:active {
  transform: scale(0.92);
}

@media (max-width: 340px) {
  .nspcf__panel {
    padding: 16px;
    gap: 12px;
  }
  .nspcf__symbol {
    font-size: 18px;
  }
  .nspcf__digit {
    font-size: 22px;
  }
  .nspcf__col {
    width: 15px;
    height: 28px;
  }
  .nspcf__btn {
    width: 32px;
    height: 32px;
  }
}
@media (prefers-reduced-motion: reduce) {
  .nspcf__digit {
    transition: none !important;
  }
}

(function () {
  var root = document.getElementById('nspcf');
  var btnPlus = document.getElementById('nspcfPlus');
  var btnMinus = document.getElementById('nspcfMinus');
  var cols = Array.prototype.slice.call(root.querySelectorAll('.nspcf__col'));

  var MIN = 0, MAX = 9999, STEP = 250;
  var value = 0;
  var H = 32;

  function toDigits(n) {
    var s = ('0000' + n).slice(-4);
    return [+s[0], +s[1], +s[2], +s[3]];
  }

  // 계산 겹: 자릿수(place)가 클수록 굴러가는 시작을 더 늦추고(delay) 더 오래 돈다(duration) —
  // 실제 기계식 계기판처럼 1의 자리가 먼저 넘어가고 그 여파가 왼쪽으로 번져 간다.
  var CASCADE = 60, BASE_DUR = 220;
  function startColumnRoll(colEl, oldD, newD, dir, place) {
    var oldEl = colEl.querySelector('.nspcf__digit--old');
    var newEl = colEl.querySelector('.nspcf__digit--new');
    var delay = place * CASCADE;
    var duration = BASE_DUR + place * 40;
    newEl.textContent = String(newD);
    newEl.style.transform = 'translateY(' + (dir * H) + 'px)';
    setTimeout(function () {
      var start = performance.now();
      function frame(now) {
        var t = Math.min(1, (now - start) / duration);
        var eased = 1 - Math.pow(1 - t, 3);
        oldEl.style.transform = 'translateY(' + (dir * H * eased).toFixed(1) + 'px)';
        newEl.style.transform = 'translateY(' + (dir * H * (eased - 1)).toFixed(1) + 'px)';
        if (t < 1) {
          requestAnimationFrame(frame);
        } else {
          oldEl.textContent = String(newD);
          oldEl.style.transform = 'translateY(0)';
          newEl.style.transform = 'translateY(' + (dir * H) + 'px)';
        }
      }
      requestAnimationFrame(frame);
    }, delay);
  }

  function commit(next) {
    next = Math.max(MIN, Math.min(MAX, next));
    if (next === value) { return; }
    var dir = next > value ? 1 : -1;
    var oldDigits = toDigits(value);
    var newDigits = toDigits(next);
    value = next;
    for (var i = 0; i < 4; i++) {
      if (oldDigits[i] !== newDigits[i]) {
        startColumnRoll(cols[i], oldDigits[i], newDigits[i], dir, 3 - i);
      }
    }
  }

  btnPlus.addEventListener('click', function () { root.classList.remove('is-demo'); stopAutoplay(); commit(value + STEP); });
  btnMinus.addEventListener('click', function () { root.classList.remove('is-demo'); stopAutoplay(); commit(value - STEP); });

  var seq = [250, 750, 1750, 4000, 9999, 0, 3333];
  var idx = 0;
  var autoplayTimer = null;
  function stopAutoplay() { if (autoplayTimer) { clearInterval(autoplayTimer); autoplayTimer = null; } }
  var reduce = window.matchMedia('(prefers-reduced-motion: reduce)').matches;
  if (!reduce) {
    autoplayTimer = setInterval(function () {
      commit(seq[idx % seq.length]);
      idx += 1;
    }, 1000);
  }
})();

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

export type NumberStepperCurrencyLiveFormatProps = {
  color?: string;
};

export default function NumberStepperCurrencyLiveFormat({
  color = "#0a4fe8",
}: NumberStepperCurrencyLiveFormatProps) {
  const rootRef = useRef<HTMLDivElement | null>(null);

  useEffect(() => {
    const root = rootRef.current;
    if (!root) return;
    const btnPlus = root.querySelector<HTMLButtonElement>(`.${styles.btnPlus}`);
    const btnMinus = root.querySelector<HTMLButtonElement>(`.${styles.btnMinus}`);
    const cols = Array.from(root.querySelectorAll<HTMLSpanElement>(`.${styles.col}`));
    if (!btnPlus || !btnMinus || cols.length !== 4) return;

    const MIN = 0, MAX = 9999, STEP = 250;
    let value = 0;
    const H = 32;

    function toDigits(n: number) {
      const s = ("0000" + n).slice(-4);
      return [+s[0], +s[1], +s[2], +s[3]];
    }

    // 계산 겹: 자릿수(place)가 클수록 굴러가는 시작을 더 늦추고(delay) 더 오래 돈다(duration) —
    // 실제 기계식 계기판처럼 1의 자리가 먼저 넘어가고 그 여파가 왼쪽으로 번져 간다.
    const CASCADE = 60, BASE_DUR = 220;
    function startColumnRoll(colEl: HTMLSpanElement, newD: number, dir: number, place: number) {
      const oldEl = colEl.querySelector<HTMLSpanElement>(`.${styles.digitOld}`);
      const newEl = colEl.querySelector<HTMLSpanElement>(`.${styles.digitNew}`);
      if (!oldEl || !newEl) return;
      const delay = place * CASCADE;
      const duration = BASE_DUR + place * 40;
      newEl.textContent = String(newD);
      newEl.style.transform = "translateY(" + dir * H + "px)";
      setTimeout(() => {
        const start = performance.now();
        function frame(now: number) {
          const t = Math.min(1, (now - start) / duration);
          const eased = 1 - Math.pow(1 - t, 3);
          oldEl!.style.transform = "translateY(" + (dir * H * eased).toFixed(1) + "px)";
          newEl!.style.transform = "translateY(" + (dir * H * (eased - 1)).toFixed(1) + "px)";
          if (t < 1) {
            requestAnimationFrame(frame);
          } else {
            oldEl!.textContent = String(newD);
            oldEl!.style.transform = "translateY(0)";
            newEl!.style.transform = "translateY(" + dir * H + "px)";
          }
        }
        requestAnimationFrame(frame);
      }, delay);
    }

    function commit(next: number) {
      next = Math.max(MIN, Math.min(MAX, next));
      if (next === value) { return; }
      const dir = next > value ? 1 : -1;
      const oldDigits = toDigits(value);
      const newDigits = toDigits(next);
      value = next;
      for (let i = 0; i < 4; i++) {
        if (oldDigits[i] !== newDigits[i]) {
          startColumnRoll(cols[i], newDigits[i], dir, 3 - i);
        }
      }
    }

    const onPlus = () => { root!.classList.remove(styles.isDemo); stopAutoplay(); commit(value + STEP); };
    const onMinus = () => { root!.classList.remove(styles.isDemo); stopAutoplay(); commit(value - STEP); };
    btnPlus.addEventListener("click", onPlus);
    btnMinus.addEventListener("click", onMinus);

    const seq = [250, 750, 1750, 4000, 9999, 0, 3333];
    let idx = 0;
    let autoplayTimer: ReturnType<typeof setInterval> | null = null;
    function stopAutoplay() {
      if (autoplayTimer) { clearInterval(autoplayTimer); autoplayTimer = null; }
    }
    const reduce = window.matchMedia("(prefers-reduced-motion: reduce)").matches;
    if (!reduce) {
      autoplayTimer = setInterval(() => {
        commit(seq[idx % seq.length]);
        idx += 1;
      }, 1000);
    }

    return () => {
      stopAutoplay();
      btnPlus!.removeEventListener("click", onPlus);
      btnMinus!.removeEventListener("click", onMinus);
    };
  }, []);

  return (
    <div ref={rootRef} className={`${styles.stage} ${styles.isDemo}`} style={{ ["--color" as string]: color }}>
      <div className={styles.panel}>
        <span className={styles.label}>코인 잔액</span>
        <div className={styles.amount}>
          <span className={styles.symbol}>◆</span>
          <span className={styles.col}>
            <span className={`${styles.digit} ${styles.digitOld}`}>0</span>
            <span className={`${styles.digit} ${styles.digitNew}`}>0</span>
          </span>
          <span className={styles.comma}>,</span>
          <span className={styles.col}>
            <span className={`${styles.digit} ${styles.digitOld}`}>0</span>
            <span className={`${styles.digit} ${styles.digitNew}`}>0</span>
          </span>
          <span className={styles.col}>
            <span className={`${styles.digit} ${styles.digitOld}`}>0</span>
            <span className={`${styles.digit} ${styles.digitNew}`}>0</span>
          </span>
          <span className={styles.col}>
            <span className={`${styles.digit} ${styles.digitOld}`}>0</span>
            <span className={`${styles.digit} ${styles.digitNew}`}>0</span>
          </span>
        </div>
        <div className={styles.row}>
          <button className={`${styles.btn} ${styles.btnMinus}`} aria-label="250 감소" type="button">−</button>
          <button className={`${styles.btn} ${styles.btnPlus}`} aria-label="250 증가" type="button">+</button>
        </div>
      </div>
    </div>
  );
}