05Select-all cascade toggle — when the parent box's select-all value turns on, each child box's checked value flips in order with a short stagger

<main class="stage">
<div class="cba is-demo" id="cba">
  <label class="cba__row cba__row--parent">
    <input type="checkbox" class="cba__input" id="cbaParent">
    <span class="cba__box" id="cbaParentBox" aria-hidden="true">
      <svg viewBox="0 0 20 20" width="14" height="14">
        <path class="cba__check" d="M4 10.5l3.5 3.5L16 5.5" fill="none" stroke="currentColor" stroke-width="2.6" stroke-linecap="round" stroke-linejoin="round"/>
        <line class="cba__dash" x1="5" y1="10" x2="15" y2="10" stroke="currentColor" stroke-width="2.6" stroke-linecap="round"/>
      </svg>
    </span>
    <span class="cba__text">Select all files</span>
  </label>
  <div class="cba__children" id="cbaChildren">
    <label class="cba__row"><input type="checkbox" class="cba__input"><span class="cba__box" aria-hidden="true"><svg viewBox="0 0 20 20" width="12" height="12"><path d="M4 10.5l3.5 3.5L16 5.5" fill="none" stroke="currentColor" stroke-width="2.6" stroke-linecap="round" stroke-linejoin="round"/></svg></span><span class="cba__text">report.pdf</span></label>
    <label class="cba__row"><input type="checkbox" class="cba__input"><span class="cba__box" aria-hidden="true"><svg viewBox="0 0 20 20" width="12" height="12"><path d="M4 10.5l3.5 3.5L16 5.5" fill="none" stroke="currentColor" stroke-width="2.6" stroke-linecap="round" stroke-linejoin="round"/></svg></span><span class="cba__text">photo.jpg</span></label>
    <label class="cba__row"><input type="checkbox" class="cba__input"><span class="cba__box" aria-hidden="true"><svg viewBox="0 0 20 20" width="12" height="12"><path d="M4 10.5l3.5 3.5L16 5.5" fill="none" stroke="currentColor" stroke-width="2.6" stroke-linecap="round" stroke-linejoin="round"/></svg></span><span class="cba__text">minutes.docx</span></label>
    <label class="cba__row"><input type="checkbox" class="cba__input"><span class="cba__box" aria-hidden="true"><svg viewBox="0 0 20 20" width="12" height="12"><path d="M4 10.5l3.5 3.5L16 5.5" fill="none" stroke="currentColor" stroke-width="2.6" stroke-linecap="round" stroke-linejoin="round"/></svg></span><span class="cba__text">sheet.xlsx</span></label>
  </div>
</div>
</main>

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

// 계산 겹: index.html 이 자식 박스마다 transition-delay 를 인덱스 × STAGGER_MS 로 계산해 심는다 —
// 부모 값이 바뀌는 순간 모든 자식의 checked 값은 동시에 바뀌지만, 화면의 배경색 전환은
// 그 계산된 지연만큼씩 늦게 시작해 계단처럼 보인다.
@include stage($stage-ink);

.cba {
  display: grid;
  gap: $sp-3;
  width: 100%;
  max-width: 260px;
}

.cba__row {
  display: flex;
  align-items: center;
  gap: $sp-3;
  cursor: pointer;
  user-select: none;
}

.cba__row--parent {
  padding-bottom: $sp-2;
  border-bottom: 1px solid rgba($subject-cream, .2);
}

.cba__children {
  display: grid;
  gap: $sp-2;
  padding-left: $sp-6;
}

.cba__input {
  position: absolute;
  width: 1px;
  height: 1px;
  opacity: 0;
  pointer-events: none;
}

.cba__box {
  flex: 0 0 auto;
  width: 20px;
  height: 20px;
  border-radius: $r-sm;
  border: 2px solid rgba($subject-cream, .4);
  background: transparent;
  color: transparent;
  display: grid;
  place-items: center;
  box-sizing: border-box;
  transition: background-color $dur-base $ease-out, border-color $dur-base $ease-out, color $dur-base $ease-out;
}

.cba__row--parent .cba__box {
  width: 24px;
  height: 24px;
}

.cba__check, .cba__dash {
  opacity: 0;
  transition: opacity $dur-quick $ease-out;
}

.cba__box--on {
  background: $subject-mint;
  border-color: $subject-mint;
  color: $subject-ink;

  .cba__check { opacity: 1; }
}

.cba__box--mixed {
  border-color: $subject-mint;

  .cba__dash { opacity: 1; }
}

.cba__input:focus-visible + .cba__box {
  outline: 2px solid $subject-blue-light;
  outline-offset: 2px;
}

.cba__text {
  color: $subject-cream;
  font-size: 13px;
  font-weight: 600;
}

.cba__row--parent .cba__text {
  font-size: 14px;
  font-weight: 700;
}

@media (max-width: 340px) {
  .cba__children { padding-left: $sp-4; }
  .cba__text { font-size: 12px; }
}

@media (prefers-reduced-motion: reduce) {
  .cba__box, .cba__check, .cba__dash { 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);
}

.cba {
  display: grid;
  gap: 12px;
  width: 100%;
  max-width: 260px;
}

.cba__row {
  display: flex;
  align-items: center;
  gap: 12px;
  cursor: pointer;
  user-select: none;
}

.cba__row--parent {
  padding-bottom: 8px;
  border-bottom: 1px solid rgba(255, 247, 230, 0.2);
}

.cba__children {
  display: grid;
  gap: 8px;
  padding-left: 24px;
}

.cba__input {
  position: absolute;
  width: 1px;
  height: 1px;
  opacity: 0;
  pointer-events: none;
}

.cba__box {
  flex: 0 0 auto;
  width: 20px;
  height: 20px;
  border-radius: 8px;
  border: 2px solid rgba(255, 247, 230, 0.4);
  background: transparent;
  color: transparent;
  display: grid;
  place-items: center;
  box-sizing: border-box;
  transition: background-color 300ms ease-out, border-color 300ms ease-out, color 300ms ease-out;
}

.cba__row--parent .cba__box {
  width: 24px;
  height: 24px;
}

.cba__check, .cba__dash {
  opacity: 0;
  transition: opacity 220ms ease-out;
}

.cba__box--on {
  background: #4cd4a6;
  border-color: #4cd4a6;
  color: #17141a;
}
.cba__box--on .cba__check {
  opacity: 1;
}

.cba__box--mixed {
  border-color: #4cd4a6;
}
.cba__box--mixed .cba__dash {
  opacity: 1;
}

.cba__input:focus-visible + .cba__box {
  outline: 2px solid #5b8cf8;
  outline-offset: 2px;
}

.cba__text {
  color: #fff7e6;
  font-size: 13px;
  font-weight: 600;
}

.cba__row--parent .cba__text {
  font-size: 14px;
  font-weight: 700;
}

@media (max-width: 340px) {
  .cba__children {
    padding-left: 16px;
  }
  .cba__text {
    font-size: 12px;
  }
}
@media (prefers-reduced-motion: reduce) {
  .cba__box, .cba__check, .cba__dash {
    transition: none;
  }
}

(function () {
  var STAGGER_MS = 90; // 계산 겹 상수: 하위 박스가 한 칸씩 늦게 바뀌는 간격
  var CYCLE_MS = 700; // 자동 루프가 전체선택을 켜고 끄는 간격
  var reduce = window.matchMedia('(prefers-reduced-motion: reduce)').matches;

  var root = document.getElementById('cba');
  var parent = document.getElementById('cbaParent');
  var parentBox = document.getElementById('cbaParentBox');
  var childrenWrap = document.getElementById('cbaChildren');
  var childInputs = Array.prototype.slice.call(childrenWrap.querySelectorAll('.cba__input'));
  var childBoxes = Array.prototype.slice.call(childrenWrap.querySelectorAll('.cba__box'));

  var isDemo = true;

  function human() {
    if (isDemo) { root.classList.remove('is-demo'); isDemo = false; }
  }

  // 계산 겹: 각 자식 박스의 transition-delay 를 인덱스 × STAGGER_MS 로 만든다 — 값 자체는
  // 동시에 바뀌지만 화면에 드러나는 시점이 계단처럼 순서를 갖는다
  childBoxes.forEach(function (b, i) {
    b.style.setProperty('transition-delay', (i * STAGGER_MS) + 'ms');
  });

  function paintParent() {
    var count = childInputs.filter(function (c) { return c.checked; }).length;
    var all = count === childInputs.length, none = count === 0;
    parent.checked = all;
    parent.indeterminate = !all && !none;
    parentBox.classList.toggle('cba__box--on', all);
    parentBox.classList.toggle('cba__box--mixed', !all && !none);
  }

  function paintChildren() {
    childInputs.forEach(function (c, i) { childBoxes[i].classList.toggle('cba__box--on', c.checked); });
  }

  childInputs.forEach(function (c) {
    c.addEventListener('change', function () { human(); paintChildren(); paintParent(); });
  });

  parent.addEventListener('change', function () {
    human();
    var next = parent.checked;
    childInputs.forEach(function (c) { c.checked = next; });
    paintChildren();
    paintParent();
  });

  var cycleStart = 0;
  var lastState = false;

  function loop(ts) {
    if (!cycleStart) cycleStart = ts;

    if (isDemo) {
      var step = Math.floor((ts - cycleStart) / CYCLE_MS) % 2 === 1;
      if (step !== lastState) {
        lastState = step;
        childInputs.forEach(function (c) { c.checked = step; });
        paintChildren();
        paintParent();
      }
    }

    requestAnimationFrame(loop);
  }

  requestAnimationFrame(loop);
})();

// SelectAllCascade — vanilla 판(run/368/demo/05-custom-checkbox-select-all-cascade/index.html) 의 React 포트.
// 각 자식 박스의 transition-delay 를 인덱스 × STAGGER_MS 로 계산해 심는다 — 값 자체는 동시에
// 바뀌지만 화면에 드러나는 시점이 계단처럼 순서를 갖는다.
import { useEffect, useRef } from "react";
import styles from "./SelectAllCascade.module.scss";

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

const CHILDREN = [
  { id: "child0", label: "보고서.pdf" },
  { id: "child1", label: "사진.jpg" },
  { id: "child2", label: "회의록.docx" },
  { id: "child3", label: "시트.xlsx" },
];

export default function SelectAllCascade() {
  const rootRef = useRef(null) as unknown as Box<HTMLDivElement>;
  const parentRef = useRef(null) as unknown as Box<HTMLInputElement>;
  const parentBoxRef = useRef(null) as unknown as Box<HTMLSpanElement>;
  const childRefs = useRef([null, null, null, null]) as unknown as Box<(HTMLInputElement | null)[]>;
  const childBoxRefs = useRef([null, null, null, null]) as unknown as Box<(HTMLSpanElement | null)[]>;

  useEffect(() => {
    const STAGGER_MS = 90; // 계산 겹 상수: 하위 박스가 한 칸씩 늦게 바뀌는 간격
    const CYCLE_MS = 700; // 자동 루프가 전체선택을 켜고 끄는 간격
    const reduce = window.matchMedia("(prefers-reduced-motion: reduce)").matches;

    const root = rootRef.current;
    const parent = parentRef.current;
    const parentBox = parentBoxRef.current;
    const childInputs = childRefs.current;
    const childBoxes = childBoxRefs.current;
    if (!root || !parent || !parentBox) return;

    let isDemo = true;

    function human() {
      if (isDemo) { root!.classList.remove(styles.isDemo); isDemo = false; }
    }

    // 계산 겹: 각 자식 박스의 transition-delay 를 인덱스 × STAGGER_MS 로 만든다
    childBoxes.forEach((b, i) => {
      if (b) b.style.setProperty("transition-delay", i * STAGGER_MS + "ms");
    });

    function paintChildren() {
      childInputs.forEach((c, i) => { childBoxes[i]?.classList.toggle(styles.boxOn, c ? c.checked : false); });
    }

    function paintParent() {
      const count = childInputs.filter((c) => c?.checked).length;
      const all = count === childInputs.length, none = count === 0;
      parent!.checked = all;
      parent!.indeterminate = !all && !none;
      parentBox!.classList.toggle(styles.boxOn, all);
      parentBox!.classList.toggle(styles.boxMixed, !all && !none);
    }

    const childHandlers = childInputs.map((c) => {
      const fn = () => { human(); paintChildren(); paintParent(); };
      c?.addEventListener("change", fn);
      return fn;
    });

    function onParentChange() {
      human();
      const next = parent!.checked;
      childInputs.forEach((c) => { if (c) c.checked = next; });
      paintChildren();
      paintParent();
    }
    parent.addEventListener("change", onParentChange);

    let cycleStart = 0;
    let lastState = false;
    let rafId = 0;

    function loop(ts: number) {
      if (!cycleStart) cycleStart = ts;

      if (isDemo) {
        const step = Math.floor((ts - cycleStart) / CYCLE_MS) % 2 === 1;
        if (step !== lastState) {
          lastState = step;
          childInputs.forEach((c) => { if (c) c.checked = step; });
          paintChildren();
          paintParent();
        }
      }

      rafId = requestAnimationFrame(loop);
    }

    rafId = requestAnimationFrame(loop);

    return () => {
      childInputs.forEach((c, i) => c?.removeEventListener("change", childHandlers[i]));
      parent.removeEventListener("change", onParentChange);
      cancelAnimationFrame(rafId);
    };
  }, []);

  return (
    <main className={styles.stage}>
      <div className={styles.cba + " " + styles.isDemo} ref={rootRef}>
        <label className={styles.cbaRow + " " + styles.cbaRowParent}>
          <input type="checkbox" className={styles.cbaInput} ref={parentRef} />
          <span className={styles.cbaBox} ref={parentBoxRef} aria-hidden="true">
            <svg viewBox="0 0 20 20" width={14} height={14}>
              <path className={styles.cbaCheck} d="M4 10.5l3.5 3.5L16 5.5" fill="none" stroke="currentColor" strokeWidth={2.6} strokeLinecap="round" strokeLinejoin="round" />
              <line className={styles.cbaDash} x1={5} y1={10} x2={15} y2={10} stroke="currentColor" strokeWidth={2.6} strokeLinecap="round" />
            </svg>
          </span>
          <span className={styles.cbaText}>파일 전체 선택</span>
        </label>
        <div className={styles.cbaChildren}>
          {CHILDREN.map((c, i) => (
            <label className={styles.cbaRow} key={c.id}>
              <input
                type="checkbox"
                className={styles.cbaInput}
                ref={(el: HTMLInputElement | null) => { childRefs.current[i] = el; }}
              />
              <span
                className={styles.cbaBox}
                ref={(el: HTMLSpanElement | null) => { childBoxRefs.current[i] = el; }}
                aria-hidden="true"
              >
                <svg viewBox="0 0 20 20" width={12} height={12}>
                  <path d="M4 10.5l3.5 3.5L16 5.5" fill="none" stroke="currentColor" strokeWidth={2.6} strokeLinecap="round" strokeLinejoin="round" />
                </svg>
              </span>
              <span className={styles.cbaText}>{c.label}</span>
            </label>
          ))}
        </div>
      </div>
    </main>
  );
}