04Quantity +/- stepper

<main class="stage">
  <div class="stepper is-demo" id="stepper" role="group" aria-label="Select quantity">
    <button class="stepper__btn" id="minus" type="button" aria-label="Decrease quantity">−</button>
    <input class="stepper__value" id="value" type="text" inputmode="numeric" pattern="[0-9]*" value="1" aria-label="Quantity">
    <button class="stepper__btn" id="plus" type="button" aria-label="Increase quantity">+</button>
  </div>
  <span id="announce" class="sr-only" aria-live="polite"></span>
</main>

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

// ── 변수 3개 ──────────────────────────────────────────
$duration: $dur-instant;   // 버튼 눌림 전환 시간
$easing: $ease-out;
$color: $stage-ink;        // 값 글자 색

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

.sr-only {
  position: absolute; width: 1px; height: 1px;
  padding: 0; margin: -1px; overflow: hidden;
  clip: rect(0, 0, 0, 0); white-space: nowrap; border: 0;
}

.stepper {
  display: flex;
  align-items: stretch;
  gap: $sp-2;
  background: $subject-cream;
  border-radius: $r-pill;
  padding: $sp-2;
  box-shadow: $shadow-raised;

  &__btn {
    box-sizing: border-box;
    width: 40px;
    border: 0;
    border-radius: 50%;
    background: #fff;
    color: $color;
    font-size: 20px;
    font-weight: 700;
    line-height: 1;
    font-family: inherit;
    cursor: pointer;
    transition: transform $duration $easing, opacity $duration $easing;

    &:active:not(:disabled) { transform: scale(.9); }
    &:disabled { opacity: .35; cursor: not-allowed; }
    &:focus-visible { outline: 2px solid $subject-blue; outline-offset: 2px; }
  }

  &__value {
    box-sizing: border-box;
    width: 52px;
    border: 0;
    background: transparent;
    text-align: center;
    font-weight: 800;
    font-size: clamp(16px, 4.6vw, 19px);
    font-family: inherit;
    color: $color;
    &:focus { outline: none; }
  }
}

@media (prefers-reduced-motion: reduce) {
  .stepper__btn { 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);
}

.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

.stepper {
  display: flex;
  align-items: stretch;
  gap: 8px;
  background: #fff7e6;
  border-radius: 999px;
  padding: 8px;
  box-shadow: 0 14px 24px rgba(23, 20, 26, 0.32);
}
.stepper__btn {
  box-sizing: border-box;
  width: 40px;
  border: 0;
  border-radius: 50%;
  background: #fff;
  color: #17141a;
  font-size: 20px;
  font-weight: 700;
  line-height: 1;
  font-family: inherit;
  cursor: pointer;
  transition: transform 140ms ease-out, opacity 140ms ease-out;
}
.stepper__btn:active:not(:disabled) {
  transform: scale(0.9);
}
.stepper__btn:disabled {
  opacity: 0.35;
  cursor: not-allowed;
}
.stepper__btn:focus-visible {
  outline: 2px solid #2f6df6;
  outline-offset: 2px;
}
.stepper__value {
  box-sizing: border-box;
  width: 52px;
  border: 0;
  background: transparent;
  text-align: center;
  font-weight: 800;
  font-size: clamp(16px, 4.6vw, 19px);
  font-family: inherit;
  color: #17141a;
}
.stepper__value:focus {
  outline: none;
}

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

(function () {
  var wrap = document.getElementById('stepper');
  var minus = document.getElementById('minus');
  var plus = document.getElementById('plus');
  var value = document.getElementById('value');
  var announce = document.getElementById('announce');
  var MIN = 1, MAX = 99;
  var n = 1;

  function render() {
    value.value = n;
    minus.disabled = n <= MIN;
    plus.disabled = n >= MAX;
    announce.textContent = 'Quantity ' + n + ' items';
  }
  function set(v) { n = Math.min(MAX, Math.max(MIN, v)); render(); }

  minus.addEventListener('click', function () { stopDemo(); set(n - 1); });
  plus.addEventListener('click', function () { stopDemo(); set(n + 1); });
  value.addEventListener('change', function () { stopDemo(); set(parseInt(value.value, 10) || MIN); });
  value.addEventListener('pointerdown', stopDemo);

  function stopDemo() {
    if (!wrap.classList.contains('is-demo')) return;
    wrap.classList.remove('is-demo');
    clearInterval(timer);
  }

  var dir = 1;
  var timer = setInterval(function () {
    if (n >= 6) dir = -1;
    if (n <= 1) dir = 1;
    set(n + dir);
  }, 260);
  render();
})();

import { useState } from "react";
import styles from "./QuantityStepper.module.scss";

export type QuantityStepperProps = {
  min?: number;
  max?: number;
  initial?: number;
  onChange?: (n: number) => void;
};

export default function QuantityStepper({
  min = 1,
  max = 99,
  initial = 1,
  onChange,
}: QuantityStepperProps) {
  const [n, setN] = useState(initial);

  const set = (v: number) => {
    const next = Math.min(max, Math.max(min, v));
    setN(next);
    onChange?.(next);
  };

  return (
    <div className={styles.stepper} role="group" aria-label="수량 선택">
      <button
        type="button"
        className={styles.btn}
        aria-label="수량 줄이기"
        disabled={n <= min}
        onClick={() => set(n - 1)}
      >
        −
      </button>
      <input
        className={styles.value}
        type="text"
        inputMode="numeric"
        pattern="[0-9]*"
        aria-label="수량"
        value={n}
        onChange={(e: any) => set(parseInt(e.target.value, 10) || min)}
      />
      <button
        type="button"
        className={styles.btn}
        aria-label="수량 늘리기"
        disabled={n >= max}
        onClick={() => set(n + 1)}
      >
        +
      </button>
      <span className={styles.srOnly} aria-live="polite">{`수량 ${n}개`}</span>
    </div>
  );
}