const codes = document.querySelectorAll(".code");
codes[0].focus();
codes.forEach((code, index) => {
code.addEventListener("keydown", (e) => {
if (e.key >= 0 && e.key < 9) {
codes[index].value = "";
setTimeout(() => {
codes[index + 1].focus();
}, 10);
} else if (e.key === "Backspace") {
setTimeout(() => {
codes[index - 1].focus();
}, 10);
}
});
});