05有効性値のリアルタイム切替 — 桁の値が埋まるたびに番号全体の有効性値が計算され表示値が変わる方式

<main class="stage">
<div class="cl is-demo" id="cl">
  <label class="cl__field">
    <input class="cl__input" id="clInput" type="text" inputmode="numeric" autocomplete="off" spellcheck="false" maxlength="16" value="">
    <span class="cl__badge" id="clBadge">
      <svg viewBox="0 0 20 20" width="14" height="14" aria-hidden="true">
        <path id="clCheck" d="M4 10.5l3.5 3.5L16 5.5" fill="none" stroke="currentColor" stroke-width="2.6" stroke-linecap="round" stroke-linejoin="round" pathLength="1" stroke-dasharray="1" stroke-dashoffset="1"/>
      </svg>
    </span>
  </label>
  <div class="cl__sum" id="clSum">加重合計値 0</div>
</div>
</main>

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

// 계산 겹: 자리별 가중 합(룬 체크섬)을 매 입력마다 다시 계산해 유효성 값을 판정한다(index.html).
@include stage($stage-ink);

.cl {
  width: 100%;
  max-width: 300px;
  display: grid;
  gap: $sp-3;
}

.cl__field {
  position: relative;
  display: block;
}

.cl__input {
  width: 100%;
  box-sizing: border-box;
  padding: $sp-3 $sp-10 $sp-3 $sp-4;
  border-radius: $r-control;
  border: 0;
  background: $subject-cream;
  color: $subject-ink;
  font-family: "SFMono-Regular", Consolas, monospace;
  font-weight: 600;
  font-size: 16px;
  letter-spacing: .05em;

  &:focus { outline: 2px solid $subject-blue-light; outline-offset: 2px; }
}

.cl__badge {
  position: absolute;
  right: $sp-3;
  top: 50%;
  transform: translateY(-50%) scale(.6);
  width: 26px;
  height: 26px;
  border-radius: 50%;
  background: rgba($subject-ink, .14);
  color: transparent;
  display: grid;
  place-items: center;
  opacity: .5;
  transition: transform $dur-quick $ease-spring, background-color $dur-quick $ease-out, color $dur-quick $ease-out, opacity $dur-quick $ease-out;

  #clCheck { transition: stroke-dashoffset $dur-enter $ease-out; }
}

.cl__badge--on {
  background: $tick-up;
  color: $subject-ink;
  opacity: 1;
  transform: translateY(-50%) scale(1);

  #clCheck { stroke-dashoffset: 0; }
}

.cl__sum {
  color: rgba($subject-cream, .72);
  font-weight: 600;
  font-size: 13px;
  font-family: "SFMono-Regular", Consolas, monospace;
}

@media (max-width: 340px) {
  .cl__input { padding: $sp-2 $sp-8 $sp-2 $sp-3; font-size: 14px; }
}

@media (prefers-reduced-motion: reduce) {
  .cl__badge, .cl__badge #clCheck { transition: none; }
}

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);
}

.cl {
  width: 100%;
  max-width: 300px;
  display: grid;
  gap: 12px;
}

.cl__field {
  position: relative;
  display: block;
}

.cl__input {
  width: 100%;
  box-sizing: border-box;
  padding: 12px 40px 12px 16px;
  border-radius: 12px;
  border: 0;
  background: #fff7e6;
  color: #17141a;
  font-family: "SFMono-Regular", Consolas, monospace;
  font-weight: 600;
  font-size: 16px;
  letter-spacing: 0.05em;
}
.cl__input:focus {
  outline: 2px solid #5b8cf8;
  outline-offset: 2px;
}

.cl__badge {
  position: absolute;
  right: 12px;
  top: 50%;
  transform: translateY(-50%) scale(0.6);
  width: 26px;
  height: 26px;
  border-radius: 50%;
  background: rgba(23, 20, 26, 0.14);
  color: transparent;
  display: grid;
  place-items: center;
  opacity: 0.5;
  transition: transform 220ms cubic-bezier(0.2, 0.8, 0.2, 1), background-color 220ms ease-out, color 220ms ease-out, opacity 220ms ease-out;
}
.cl__badge #clCheck {
  transition: stroke-dashoffset 600ms ease-out;
}

.cl__badge--on {
  background: #3ddc97;
  color: #17141a;
  opacity: 1;
  transform: translateY(-50%) scale(1);
}
.cl__badge--on #clCheck {
  stroke-dashoffset: 0;
}

.cl__sum {
  color: rgba(255, 247, 230, 0.72);
  font-weight: 600;
  font-size: 13px;
  font-family: "SFMono-Regular", Consolas, monospace;
}

@media (max-width: 340px) {
  .cl__input {
    padding: 8px 32px 8px 12px;
    font-size: 14px;
  }
}
@media (prefers-reduced-motion: reduce) {
  .cl__badge, .cl__badge #clCheck {
    transition: none;
  }
}

(function () {
  var root = document.getElementById('cl');
  var input = document.getElementById('clInput');
  var badge = document.getElementById('clBadge');
  var sumLabel = document.getElementById('clSum');

  // 계산 겹: 자리별 가중 합(오른쪽부터 한 자리씩 건너 2배) — 룬 체크섬을 매 입력마다 다시 계산한다.
  function luhnSum(digits) {
    var sum = 0, dbl = false;
    for (var i = digits.length - 1; i >= 0; i--) {
      var d = digits.charCodeAt(i) - 48;
      if (dbl) { d *= 2; if (d > 9) d -= 9; }
      sum += d;
      dbl = !dbl;
    }
    return sum;
  }

  function paint(digits) {
    var sum = digits.length ? luhnSum(digits) : 0;
    var valid = digits.length >= 13 && sum % 10 === 0;
    sumLabel.textContent = '加重合計値 ' + sum;
    badge.classList.toggle('cl__badge--on', valid);
  }

  input.addEventListener('input', function () {
    root.classList.remove('is-demo');
    stopAutoplay();
    var digits = input.value.replace(/\D/g, '').slice(0, 16);
    input.value = digits;
    paint(digits);
  });

  // 자동 루프: 유효 번호를 한 자리씩 채웠다가, 마지막 자리를 잘못된 값으로 바꿔 무효 상태도 보여준다.
  var VALID = '9999999999999995';
  var INVALID = '9999999999999990';
  var SEQ = [];
  for (var i = 0; i <= VALID.length; i++) SEQ.push(VALID.slice(0, i));
  SEQ.push(INVALID);
  SEQ.push(VALID);
  for (var k = VALID.length - 1; k >= 0; k--) SEQ.push(VALID.slice(0, k));
  var si = 0;
  var autoTimer = null;
  function autoTick() {
    var digits = SEQ[si];
    input.value = digits;
    paint(digits);
    si = (si + 1) % SEQ.length;
  }
  function stopAutoplay() { if (autoTimer) { clearInterval(autoTimer); autoTimer = null; } }
  var reduce = window.matchMedia('(prefers-reduced-motion: reduce)').matches;
  if (!reduce) { autoTimer = setInterval(autoTick, 180); autoTick(); }
  else { autoTick(); }
})();

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

type Box<T> = { current: T };

const CHECK_PATH = "M4 10.5l3.5 3.5L16 5.5";

export default function LuhnLiveCheckmark() {
  const rootRef = useRef(null) as unknown as Box<HTMLDivElement | null>;

  useEffect(() => {
    const root = rootRef.current;
    if (!root) return;
    const input = root.querySelector(`.${styles.input}`) as HTMLInputElement | null;
    const badge = root.querySelector(`.${styles.badge}`) as HTMLElement | null;
    const sumLabel = root.querySelector(`.${styles.sum}`) as HTMLElement | null;
    if (!input || !badge || !sumLabel) return;

    // 계산 겹: 자리별 가중 합(오른쪽부터 한 자리씩 건너 2배) — 룬 체크섬을 매 입력마다 다시 계산한다.
    function luhnSum(digits: string) {
      let sum = 0, dbl = false;
      for (let i = digits.length - 1; i >= 0; i--) {
        let d = digits.charCodeAt(i) - 48;
        if (dbl) { d *= 2; if (d > 9) d -= 9; }
        sum += d;
        dbl = !dbl;
      }
      return sum;
    }

    function paint(digits: string) {
      const sum = digits.length ? luhnSum(digits) : 0;
      const valid = digits.length >= 13 && sum % 10 === 0;
      sumLabel!.textContent = "가중 합 값 " + sum;
      badge!.classList.toggle(styles["badge--on"], valid);
    }

    function onInput() {
      root!.classList.remove(styles["is-demo"]);
      stopAutoplay();
      const digits = input!.value.replace(/\D/g, "").slice(0, 16);
      input!.value = digits;
      paint(digits);
    }
    input.addEventListener("input", onInput);

    // 자동 루프: 유효 번호를 한 자리씩 채웠다가, 마지막 자리를 잘못된 값으로 바꿔 무효 상태도 보여준다.
    const VALID = "9999999999999995";
    const INVALID = "9999999999999990";
    const SEQ: string[] = [];
    for (let i = 0; i <= VALID.length; i++) SEQ.push(VALID.slice(0, i));
    SEQ.push(INVALID);
    SEQ.push(VALID);
    for (let k = VALID.length - 1; k >= 0; k--) SEQ.push(VALID.slice(0, k));
    let si = 0;
    let autoTimer: number | null = null;
    function autoTick() {
      const digits = SEQ[si];
      input!.value = digits;
      paint(digits);
      si = (si + 1) % SEQ.length;
    }
    function stopAutoplay() {
      if (autoTimer !== null) { window.clearInterval(autoTimer); autoTimer = null; }
    }
    const reduce = window.matchMedia("(prefers-reduced-motion: reduce)").matches;
    if (!reduce) { autoTimer = window.setInterval(autoTick, 180); autoTick(); }
    else { autoTick(); }

    return () => {
      stopAutoplay();
      input.removeEventListener("input", onInput);
    };
  }, []);

  return (
    <div ref={rootRef} className={`${styles.stage} ${styles.cl} ${styles["is-demo"]}`}>
      <label className={styles.field}>
        <input className={styles.input} type="text" inputMode="numeric" autoComplete="off" spellCheck={false} maxLength={16} defaultValue="" />
        <span className={styles.badge}>
          <svg viewBox="0 0 20 20" width="14" height="14" aria-hidden="true">
            <path className={styles.check} d={CHECK_PATH} fill="none" stroke="currentColor" strokeWidth={2.6} strokeLinecap="round" strokeLinejoin="round" pathLength={1} strokeDasharray={1} strokeDashoffset={1} />
          </svg>
        </span>
      </label>
      <div className={styles.sum}>가중 합 값 0</div>
    </div>
  );
}