OTP input

<div class="otw">
  <span class="otlabel">인증번호 6자리</span>
  <div class="otgroup" role="group" aria-label="인증번호 입력">
    <input class="otcell" maxlength="1" inputmode="numeric" aria-label="1번째 자리">
    <input class="otcell" maxlength="1" inputmode="numeric" aria-label="2번째 자리">
    <input class="otcell" maxlength="1" inputmode="numeric" aria-label="3번째 자리">
    <input class="otcell" maxlength="1" inputmode="numeric" aria-label="4번째 자리">
    <input class="otcell" maxlength="1" inputmode="numeric" aria-label="5번째 자리">
    <input class="otcell" maxlength="1" inputmode="numeric" aria-label="6번째 자리">
  </div>
  <p class="otstatus" id="otstatus">문자로 받은 6자리를 입력하세요</p>
</div>

.otw{position:absolute;inset:0;display:grid;place-items:center;gap:10px}
.otlabel{color:var(--muted);font-size:10px}
.otgroup{display:flex;gap:6px}
.otcell{width:26px;height:32px;text-align:center;font-size:15px;font-weight:700;border:1px solid var(--line);border-radius:8px;background:var(--surface);color:var(--fg)}
.otcell[data-filled]{border-color:var(--accent);color:var(--accent)}
.otstatus{font-size:10px;color:var(--muted)}

const cells = [...document.querySelectorAll('.otcell')];
const status = document.getElementById('otstatus');
cells.forEach((c, i) => {
  c.addEventListener('input', () => {
    auto = false;
    c.toggleAttribute('data-filled', !!c.value);
    if (c.value && cells[i + 1]) cells[i + 1].focus();
  });
  c.addEventListener('keydown', (e) => {
    if (e.key === 'Backspace' && !c.value && cells[i - 1]) { auto = false; cells[i - 1].focus(); }
  });
});
let auto = true;
function loop() {
  if (!auto) return;
  let i = 0;
  const t = setInterval(() => {
    if (!auto) return clearInterval(t);
    cells[i].value = String(Math.floor(Math.random() * 10));
    cells[i].setAttribute('data-filled', '');
    i++;
    if (i >= cells.length) {
      clearInterval(t);
      status.textContent = '확인 중…';
      setTimeout(() => {
        if (!auto) return;
        status.textContent = '인증 완료';
        setTimeout(() => {
          if (!auto) return;
          cells.forEach((c) => { c.value = ''; c.removeAttribute('data-filled'); });
          status.textContent = '문자로 받은 6자리를 입력하세요';
          setTimeout(loop, 900);
        }, 1200);
      }, 500);
    }
  }, 220);
}
setTimeout(loop, 500);