03Currency input with auto comma

<main class="stage">
  <div class="field is-demo" id="field">
    <label class="field__label" for="amount-input">Donation amount</label>
    <div class="field__frame">
      <span class="field__prefix" aria-hidden="true">₩</span>
      <input class="field__input" id="amount-input" type="text" inputmode="numeric" placeholder="0" aria-describedby="amount-hint">
    </div>
    <p class="field__hint" id="amount-hint">Type digits and thousands separators are added automatically</p>
  </div>
</main>

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

// ── 변수 3개 ──────────────────────────────────────────
$duration: $dur-quick;
$easing: $ease-out;
$color: $subject-blue;

// ── 데모 무대 ──────────────────────────────────────────
@include stage($stage-orange);

.field {
  box-sizing: border-box;
  width: min(260px, 84vw);
  background: $subject-cream;
  border-radius: $r-card;
  padding: $sp-5 $sp-5 $sp-4;
  box-shadow: $shadow-raised;

  &__label {
    display: block;
    margin: 0 0 $sp-2;
    font-weight: 700;
    font-size: 13px;
    line-height: 1;
    font-family: inherit;
    color: $stage-ink;
  }

  &__frame {
    display: flex;
    align-items: center;
    gap: $sp-2;
    border: 2px solid transparent;
    border-radius: $r-control;
    padding: $sp-3 $sp-4;
    background: #fff;
    transition: border-color $duration $easing;
    &:focus-within { border-color: $color; }
  }

  &__prefix {
    font-weight: 700;
    font-size: clamp(15px, 4.4vw, 18px);
    font-family: inherit;
    color: rgba(23, 20, 26, .72);
  }

  &__input {
    box-sizing: border-box;
    flex: 1 1 auto;
    min-width: 0;
    border: 0;
    padding: 0;
    text-align: right;
    font-weight: 700;
    font-size: clamp(15px, 4.4vw, 18px);
    font-family: inherit;
    color: $stage-ink;
    background: transparent;
    &:focus { outline: none; }
  }

  &__hint {
    margin: $sp-2 0 0;
    font-size: 12px;
    line-height: 1.4;
    font-family: inherit;
    color: rgba(23, 20, 26, .6);
  }
}

@media (prefers-reduced-motion: reduce) {
  .field__frame { transition: none; }
}

html, body {
  margin: 0;
  overflow: hidden;
}

.stage {
  box-sizing: border-box;
  min-height: 100vh;
  display: grid;
  place-items: center;
  margin: 0;
  background: #ff4d1f;
  font-family: -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  padding: clamp(8px, 4vw, 24px);
}

.field {
  box-sizing: border-box;
  width: min(260px, 84vw);
  background: #fff7e6;
  border-radius: 16px;
  padding: 20px 20px 16px;
  box-shadow: 0 14px 24px rgba(23, 20, 26, 0.32);
}
.field__label {
  display: block;
  margin: 0 0 8px;
  font-weight: 700;
  font-size: 13px;
  line-height: 1;
  font-family: inherit;
  color: #17141a;
}
.field__frame {
  display: flex;
  align-items: center;
  gap: 8px;
  border: 2px solid transparent;
  border-radius: 12px;
  padding: 12px 16px;
  background: #fff;
  transition: border-color 220ms ease-out;
}
.field__frame:focus-within {
  border-color: #2f6df6;
}
.field__prefix {
  font-weight: 700;
  font-size: clamp(15px, 4.4vw, 18px);
  font-family: inherit;
  color: rgba(23, 20, 26, 0.72);
}
.field__input {
  box-sizing: border-box;
  flex: 1 1 auto;
  min-width: 0;
  border: 0;
  padding: 0;
  text-align: right;
  font-weight: 700;
  font-size: clamp(15px, 4.4vw, 18px);
  font-family: inherit;
  color: #17141a;
  background: transparent;
}
.field__input:focus {
  outline: none;
}
.field__hint {
  margin: 8px 0 0;
  font-size: 12px;
  line-height: 1.4;
  font-family: inherit;
  color: rgba(23, 20, 26, 0.6);
}

@media (prefers-reduced-motion: reduce) {
  .field__frame {
    transition: none;
  }
}

(function () {
  var field = document.getElementById('field');
  var input = document.getElementById('amount-input');

  function format(v) {
    var d = v.replace(/\D/g, '').replace(/^0+(?=\d)/, '').slice(0, 12);
    return d ? Number(d).toLocaleString('ko-KR') : '';
  }

  input.addEventListener('input', function () {
    input.value = format(input.value);
  });

  function stopDemo() {
    if (!field.classList.contains('is-demo')) return;
    field.classList.remove('is-demo');
    clearInterval(timer);
    input.value = '';
  }
  input.addEventListener('pointerdown', stopDemo);
  input.addEventListener('keydown', stopDemo);

  var digits = '1500000';
  var i = 0;
  var timer = setInterval(function () {
    if (i > digits.length) { i = 0; input.value = ''; return; }
    input.value = format(digits.slice(0, i));
    i++;
  }, 190);
})();

import { useRef, useState } from "react";
import styles from "./CurrencyInput.module.scss";

export type CurrencyInputProps = {
  label?: string;
  hint?: string;
  symbol?: string;
};

function format(raw: string): string {
  const d = raw.replace(/\D/g, "").replace(/^0+(?=\d)/, "").slice(0, 12);
  return d ? Number(d).toLocaleString("ko-KR") : "";
}

export default function CurrencyInput({
  label = "후원 금액",
  hint = "숫자만 입력하면 천 단위 콤마가 자동으로 붙습니다",
  symbol = "₩",
}: CurrencyInputProps) {
  const [value, setValue] = useState("");
  const id = useRef("amount-input-" + Math.random().toString(36).slice(2)).current;

  return (
    <div className={styles.field}>
      <label className={styles.label} htmlFor={id}>{label}</label>
      <div className={styles.frame}>
        <span className={styles.prefix} aria-hidden="true">{symbol}</span>
        <input
          className={styles.input}
          id={id}
          type="text"
          inputMode="numeric"
          placeholder="0"
          aria-describedby={id + "-hint"}
          value={value}
          onChange={(e: any) => setValue(format(e.target.value))}
        />
      </div>
      <p className={styles.hint} id={id + "-hint"}>{hint}</p>
    </div>
  );
}