06Auto-growing textarea

<main class="stage">
  <div class="grow is-demo" id="wrap">
    <label class="grow__label" for="review">Write a review</label>
    <textarea class="grow__area" id="review" rows="1" placeholder="Tell us how this product worked for you"></textarea>
  </div>
</main>

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

// ── 변수 3개 ──────────────────────────────────────────
$duration: $dur-quick;    // 높이가 늘어나는 시간
$easing: $ease-out;
$color: $subject-blue;    // 포커스 테두리 색

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

.grow {
  box-sizing: border-box;
  width: min(280px, 86vw);
  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;
  }

  &__area {
    box-sizing: border-box;
    display: block;
    width: 100%;
    min-height: 40px;
    max-height: 132px;
    resize: none;
    overflow-y: auto;
    border: 2px solid transparent;
    border-radius: $r-control;
    padding: $sp-3 $sp-4;
    font-weight: 500;
    font-size: clamp(13px, 3.8vw, 15px);
    line-height: 1.4;
    font-family: inherit;
    color: $stage-ink;
    background: #fff;
    transition: height $duration $easing, border-color $duration $easing;

    &:focus { outline: none; border-color: $color; }
  }
}

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

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

.stage {
  box-sizing: border-box;
  min-height: 100vh;
  display: grid;
  place-items: center;
  margin: 0;
  background: #ffd23f;
  font-family: -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  padding: clamp(8px, 4vw, 24px);
}

.grow {
  box-sizing: border-box;
  width: min(280px, 86vw);
  background: #fff7e6;
  border-radius: 16px;
  padding: 20px 20px 16px;
  box-shadow: 0 14px 24px rgba(23, 20, 26, 0.32);
}
.grow__label {
  display: block;
  margin: 0 0 8px;
  font-weight: 700;
  font-size: 13px;
  line-height: 1;
  font-family: inherit;
  color: #17141a;
}
.grow__area {
  box-sizing: border-box;
  display: block;
  width: 100%;
  min-height: 40px;
  max-height: 132px;
  resize: none;
  overflow-y: auto;
  border: 2px solid transparent;
  border-radius: 12px;
  padding: 12px 16px;
  font-weight: 500;
  font-size: clamp(13px, 3.8vw, 15px);
  line-height: 1.4;
  font-family: inherit;
  color: #17141a;
  background: #fff;
  transition: height 220ms ease-out, border-color 220ms ease-out;
}
.grow__area:focus {
  outline: none;
  border-color: #2f6df6;
}

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

(function () {
  var wrap = document.getElementById('wrap');
  var area = document.getElementById('review');
  var MAX = 132;

  function resize() {
    area.style.height = 'auto';
    area.style.height = Math.min(area.scrollHeight, MAX) + 'px';
  }
  area.addEventListener('input', resize);

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

  var full = 'The delivery was fast and the packaging was careful.\\nThe colors look almost exactly like the photos.\\nI will order again, thank you!';
  var i = 0;
  var timer = setInterval(function () {
    if (i > full.length) { i = 0; area.value = ''; resize(); return; }
    area.value = full.slice(0, i);
    resize();
    i += 2;
  }, 90);
})();

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

export type TextareaAutogrowProps = {
  label?: string;
  placeholder?: string;
  maxHeight?: number;
};

export default function TextareaAutogrow({
  label = "후기 작성",
  placeholder = "이 상품을 써 본 느낌을 알려주세요",
  maxHeight = 132,
}: TextareaAutogrowProps) {
  const [value, setValue] = useState("");
  const ref = useRef<HTMLTextAreaElement | null>(null);

  const resize = () => {
    const el = ref.current;
    if (!el) return;
    el.style.height = "auto";
    el.style.height = Math.min(el.scrollHeight, maxHeight) + "px";
  };

  return (
    <div className={styles.grow}>
      <label className={styles.label}>{label}</label>
      <textarea
        ref={ref}
        className={styles.area}
        rows={1}
        placeholder={placeholder}
        value={value}
        style={{ maxHeight }}
        onChange={(e: any) => {
          setValue(e.target.value);
          resize();
        }}
      />
    </div>
  );
}