04Mask value toggle — when the masking value turns on, all but the first few digit values switch to a symbol value

<main class="stage">
<div class="cm is-demo" id="cm">
  <div class="cm__row" id="cmRow"></div>
  <button type="button" class="cm__toggle" id="cmToggle" aria-pressed="false">Toggle mask value</button>
</div>
</main>

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

// 계산 겹: 가림 값 전환이 자릿수 값 순서대로 STAGGER_MS 씩 늦게 퍼진다(index.html --i, transition-delay).
@include stage($stage-paper);

.cm {
  width: 100%;
  max-width: 320px;
  display: grid;
  gap: $sp-5;
  justify-items: center;
}

.cm__row {
  display: flex;
  align-items: center;
  background: $subject-ink;
  border-radius: $r-control;
  padding: $sp-4;
  box-sizing: border-box;
  width: 100%;
}

.cm__group {
  position: relative;
  width: 13px;
  height: 20px;
  margin-right: 0;

  &--gap { margin-left: $sp-2; }
}

.cm__digit,
.cm__mask {
  position: absolute;
  inset: 0;
  display: grid;
  place-items: center;
  font-family: "SFMono-Regular", Consolas, monospace;
  font-weight: 600;
  font-size: 16px;
  color: $subject-cream;
  transition: transform $dur-quick $ease-spring, opacity $dur-quick $ease-out;
  transition-delay: calc(var(--i, 0) * 45ms);
}

.cm__digit--fixed { position: static; transition: none; }

.cm__mask {
  opacity: 0;
  transform: scale(.4);
}

.cm--masked {
  .cm__digit:not(.cm__digit--fixed) { opacity: 0; transform: scale(.4); }
  .cm__mask { opacity: 1; transform: scale(1); }
}

.cm__toggle {
  border: 0;
  border-radius: $r-pill;
  padding: $sp-2 $sp-5;
  background: $subject-ink;
  color: $subject-cream;
  font-weight: 700;
  font-size: 13px;
  cursor: pointer;
  transition: transform $dur-instant $ease-out;

  &:active { transform: scale(.95); }
  &:focus-visible { outline: 2px solid $subject-blue-deep; outline-offset: 2px; }
}

@media (max-width: 340px) {
  .cm__row { padding: $sp-3; }
  .cm__group { width: 11px; }
  .cm__digit, .cm__mask { font-size: 14px; }
}

@media (prefers-reduced-motion: reduce) {
  .cm__digit, .cm__mask { transition: none; transition-delay: 0ms; }
  .cm__toggle { transition: none; }
}

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);
}

.cm {
  width: 100%;
  max-width: 320px;
  display: grid;
  gap: 20px;
  justify-items: center;
}

.cm__row {
  display: flex;
  align-items: center;
  background: #17141a;
  border-radius: 12px;
  padding: 16px;
  box-sizing: border-box;
  width: 100%;
}

.cm__group {
  position: relative;
  width: 13px;
  height: 20px;
  margin-right: 0;
}
.cm__group--gap {
  margin-left: 8px;
}

.cm__digit,
.cm__mask {
  position: absolute;
  inset: 0;
  display: grid;
  place-items: center;
  font-family: "SFMono-Regular", Consolas, monospace;
  font-weight: 600;
  font-size: 16px;
  color: #fff7e6;
  transition: transform 220ms cubic-bezier(0.2, 0.8, 0.2, 1), opacity 220ms ease-out;
  transition-delay: calc(var(--i, 0) * 45ms);
}

.cm__digit--fixed {
  position: static;
  transition: none;
}

.cm__mask {
  opacity: 0;
  transform: scale(0.4);
}

.cm--masked .cm__digit:not(.cm__digit--fixed) {
  opacity: 0;
  transform: scale(0.4);
}
.cm--masked .cm__mask {
  opacity: 1;
  transform: scale(1);
}

.cm__toggle {
  border: 0;
  border-radius: 999px;
  padding: 8px 20px;
  background: #17141a;
  color: #fff7e6;
  font-weight: 700;
  font-size: 13px;
  cursor: pointer;
  transition: transform 140ms ease-out;
}
.cm__toggle:active {
  transform: scale(0.95);
}
.cm__toggle:focus-visible {
  outline: 2px solid #0a4fe8;
  outline-offset: 2px;
}

@media (max-width: 340px) {
  .cm__row {
    padding: 12px;
  }
  .cm__group {
    width: 11px;
  }
  .cm__digit, .cm__mask {
    font-size: 14px;
  }
}
@media (prefers-reduced-motion: reduce) {
  .cm__digit, .cm__mask {
    transition: none;
    transition-delay: 0ms;
  }
  .cm__toggle {
    transition: none;
  }
}

(function () {
  var root = document.getElementById('cm');
  var row = document.getElementById('cmRow');
  var btn = document.getElementById('cmToggle');
  var DIGITS = '9999999999999995';
  var KEEP = 4; // 앞의 몇 자리 값은 항상 그대로
  var STAGGER_MS = 45; // 계산 겹: 자릿수 값마다 이만큼씩 늦게 전환된다

  var cells = [];
  DIGITS.split('').forEach(function (ch, i) {
    var group = document.createElement('span');
    group.className = 'cm__group';
    if (i > 0 && i % 4 === 0) group.classList.add('cm__group--gap');
    if (i < KEEP) {
      group.innerHTML = '<span class="cm__digit cm__digit--fixed">' + ch + '</span>';
    } else {
      var idx = i - KEEP;
      group.style.setProperty('--i', idx);
      group.innerHTML =
        '<span class="cm__digit">' + ch + '</span>' +
        '<span class="cm__mask">•</span>';
      cells.push(group);
    }
    row.appendChild(group);
  });

  var masked = false;
  function paint() {
    root.classList.toggle('cm--masked', masked);
    btn.setAttribute('aria-pressed', String(masked));
  }

  function toggle() {
    masked = !masked;
    paint();
  }

  btn.addEventListener('click', function () {
    root.classList.remove('is-demo');
    stopAutoplay();
    toggle();
  });

  var autoTimer = null;
  function stopAutoplay() { if (autoTimer) { clearInterval(autoTimer); autoTimer = null; } }
  var reduce = window.matchMedia('(prefers-reduced-motion: reduce)').matches;
  if (!reduce) { autoTimer = setInterval(toggle, 1500); }
  else { masked = true; paint(); }
})();

import { useEffect, useRef } from "react";
import type { CSSProperties } from "react";
import styles from "./MaskToggleReveal.module.scss";

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

const DIGITS = "9999999999999995";
const KEEP = 4; // 앞의 몇 자리 값은 항상 그대로
const STAGGER_MS = 45; // 계산 겹: 자릿수 값마다 이만큼씩 늦게 전환된다

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

  useEffect(() => {
    const root = rootRef.current;
    if (!root) return;
    const btn = root.querySelector(`.${styles.toggle}`) as HTMLButtonElement | null;
    if (!btn) return;

    let masked = false;
    function paint() {
      root!.classList.toggle(styles["root--masked"], masked);
      btn!.setAttribute("aria-pressed", String(masked));
    }
    function toggle() { masked = !masked; paint(); }

    function onClick() {
      root!.classList.remove(styles["is-demo"]);
      stopAutoplay();
      toggle();
    }
    btn.addEventListener("click", onClick);

    let autoTimer: number | null = null;
    function stopAutoplay() {
      if (autoTimer !== null) { window.clearInterval(autoTimer); autoTimer = null; }
    }
    const reduce = window.matchMedia("(prefers-reduced-motion: reduce)").matches;
    if (!reduce) { autoTimer = window.setInterval(toggle, 1500); }
    else { masked = true; paint(); }

    return () => {
      stopAutoplay();
      btn.removeEventListener("click", onClick);
    };
  }, []);

  const cells = DIGITS.split("").map((ch, i) => ({
    ch,
    gapBefore: i > 0 && i % 4 === 0,
    fixed: i < KEEP,
    idx: i - KEEP,
  }));

  return (
    <div ref={rootRef} className={`${styles.stage} ${styles.cm} ${styles["is-demo"]}`}>
      <div className={styles.row}>
        {cells.map((c, i) => (
          <span key={i} className={`${styles.group} ${c.gapBefore ? styles["group--gap"] : ""}`}>
            {c.fixed ? (
              <span className={`${styles.digit} ${styles["digit--fixed"]}`}>{c.ch}</span>
            ) : (
              <>
                <span className={styles.digit} style={{ transitionDelay: `${c.idx * STAGGER_MS}ms` } as CSSProperties}>{c.ch}</span>
                <span className={styles.mask} style={{ transitionDelay: `${c.idx * STAGGER_MS}ms` } as CSSProperties}>•</span>
              </>
            )}
          </span>
        ))}
      </div>
      <button type="button" className={styles.toggle} aria-pressed="false">가림 값 전환</button>
    </div>
  );
}