04Nút tải thêm danh sách

<main class="stage">
  <div class="lm-list is-demo">
    <ul class="lm-rows">
      <li class="lm-row">Thông báo cập nhật bảng tin</li>
      <li class="lm-row">Bảo trì định kỳ tháng 9</li>
      <li class="lm-row lm-row--pending" data-n="1">Ghi chú phát hành tính năng mới</li>
      <li class="lm-row lm-row--pending" data-n="2">Công bố người trúng sự kiện</li>
      <li class="lm-row lm-row--pending" data-n="3">Cập nhật điều khoản dịch vụ</li>
    </ul>
    <button class="lm-btn" type="button">
      <svg class="lm-btn__icon" viewBox="0 0 256 256" aria-hidden="true"><g fill="currentColor"><path d="M216 128a88 88 0 1 1-88-88a88 88 0 0 1 88 88" opacity=".2"/><path d="M240 56v48a8 8 0 0 1-8 8h-48a8 8 0 0 1 0-16h27.4l-26.59-24.36l-.25-.24a80 80 0 1 0-1.67 114.78a8 8 0 0 1 11 11.63A95.44 95.44 0 0 1 128 224h-1.32a96 96 0 1 1 69.07-164L224 85.8V56a8 8 0 1 1 16 0"/></g></svg>
      <span class="lm-btn__label">Tải thêm</span>
    </button>
  </div>
</main>

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

$duration: $dur-enter;                                 // 새 행이 밀려 올라오는 시간
$easing: $ease-spring;
$color: $subject-blue;                                 // 신뢰감 있는 브랜드 컬러(밝은 SaaS 톤)

@include stage($stage-paper);

.lm-list {
  width: min(260px, 82vw);
  display: flex;
  flex-direction: column;
  gap: $sp-3;
}

.lm-rows { list-style: none; margin: 0; padding: 0; display: flex; flex-direction: column; gap: $sp-2; }
.lm-row {
  padding: $sp-3;
  border-radius: $r-sm;
  background: #eef4ff;                 // $subject-blue 를 흰 배경에 6% 섞은 불투명 톤
  font-size: 13px;
  color: $stage-ink;
}
.lm-row--pending {
  max-height: 0;
  opacity: 0;
  transform: translateY(10px);
  overflow: hidden;
  padding-top: 0;
  padding-bottom: 0;
  margin: 0;
  transition: max-height $duration $easing, opacity $duration $easing, transform $duration $easing, padding $duration $easing;
}
.lm-list.has-loaded .lm-row--pending { max-height: 40px; opacity: 1; transform: translateY(0); padding-top: $sp-3; padding-bottom: $sp-3; }
.lm-list.has-loaded .lm-row--pending[data-n="2"] { transition-delay: 90ms; }
.lm-list.has-loaded .lm-row--pending[data-n="3"] { transition-delay: 180ms; }

.lm-btn {
  align-self: center;
  display: inline-flex;
  align-items: center;
  gap: $sp-2;
  border: 1px solid $color;
  background: $stage-paper;
  color: $color;
  font-weight: 700;
  font-size: 13px;
  border-radius: $r-pill;
  padding: $sp-2 $sp-5;
  cursor: pointer;
  font-family: inherit;
}
.lm-btn:focus-visible { outline: 2px solid $color; outline-offset: 2px; }
.lm-btn:disabled { opacity: .5; cursor: default; }
.lm-btn__icon { width: 14px; height: 14px; opacity: 0; width: 0; transition: opacity $dur-quick, width $dur-quick; }
.lm-list.is-loading .lm-btn__icon { opacity: 1; width: 14px; animation: lm-spin .6s linear infinite; }

@keyframes lm-spin { to { transform: rotate(360deg); } }

// 데모 강제 루프 — 스피너 회전 → 대기 행 순차 등장 → 리셋 을 한 keyframes 로
.lm-list.is-demo .lm-btn__icon {
  opacity: 1; width: 14px;
  animation: lm-loop-spin $dur-loop linear infinite;
}
.lm-list.is-demo .lm-row--pending {
  animation: lm-loop-row $dur-loop $easing infinite;
}
.lm-list.is-demo .lm-row--pending[data-n="2"] { animation-delay: 60ms; }
.lm-list.is-demo .lm-row--pending[data-n="3"] { animation-delay: 120ms; }

@keyframes lm-loop-spin {
  0%, 15%   { transform: rotate(0deg); opacity: 1; }
  30%       { transform: rotate(360deg); opacity: 1; }
  35%, 100% { opacity: 0; }
}
@keyframes lm-loop-row {
  0%, 30%   { max-height: 0; opacity: 0; transform: translateY(10px); padding-top: 0; padding-bottom: 0; }
  55%, 85%  { max-height: 40px; opacity: 1; transform: translateY(0); padding-top: $sp-3; padding-bottom: $sp-3; }
  100%      { max-height: 0; opacity: 0; transform: translateY(10px); padding-top: 0; padding-bottom: 0; }
}

@media (prefers-reduced-motion: reduce) {
  .lm-row--pending, .lm-btn__icon { transition: none; animation: none; }
  .lm-list.has-loaded .lm-row--pending { opacity: 1; transform: 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);
}

.lm-list {
  width: min(260px, 82vw);
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.lm-rows {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.lm-row {
  padding: 12px;
  border-radius: 8px;
  background: #eef4ff;
  font-size: 13px;
  color: #17141a;
}

.lm-row--pending {
  max-height: 0;
  opacity: 0;
  transform: translateY(10px);
  overflow: hidden;
  padding-top: 0;
  padding-bottom: 0;
  margin: 0;
  transition: max-height 600ms cubic-bezier(0.2, 0.8, 0.2, 1), opacity 600ms cubic-bezier(0.2, 0.8, 0.2, 1), transform 600ms cubic-bezier(0.2, 0.8, 0.2, 1), padding 600ms cubic-bezier(0.2, 0.8, 0.2, 1);
}

.lm-list.has-loaded .lm-row--pending {
  max-height: 40px;
  opacity: 1;
  transform: translateY(0);
  padding-top: 12px;
  padding-bottom: 12px;
}

.lm-list.has-loaded .lm-row--pending[data-n="2"] {
  transition-delay: 90ms;
}

.lm-list.has-loaded .lm-row--pending[data-n="3"] {
  transition-delay: 180ms;
}

.lm-btn {
  align-self: center;
  display: inline-flex;
  align-items: center;
  gap: 8px;
  border: 1px solid #2f6df6;
  background: #ffffff;
  color: #2f6df6;
  font-weight: 700;
  font-size: 13px;
  border-radius: 999px;
  padding: 8px 20px;
  cursor: pointer;
  font-family: inherit;
}

.lm-btn:focus-visible {
  outline: 2px solid #2f6df6;
  outline-offset: 2px;
}

.lm-btn:disabled {
  opacity: 0.5;
  cursor: default;
}

.lm-btn__icon {
  width: 14px;
  height: 14px;
  opacity: 0;
  width: 0;
  transition: opacity 220ms, width 220ms;
}

.lm-list.is-loading .lm-btn__icon {
  opacity: 1;
  width: 14px;
  animation: lm-spin 0.6s linear infinite;
}

@keyframes lm-spin {
  to {
    transform: rotate(360deg);
  }
}
.lm-list.is-demo .lm-btn__icon {
  opacity: 1;
  width: 14px;
  animation: lm-loop-spin 2s linear infinite;
}

.lm-list.is-demo .lm-row--pending {
  animation: lm-loop-row 2s cubic-bezier(0.2, 0.8, 0.2, 1) infinite;
}

.lm-list.is-demo .lm-row--pending[data-n="2"] {
  animation-delay: 60ms;
}

.lm-list.is-demo .lm-row--pending[data-n="3"] {
  animation-delay: 120ms;
}

@keyframes lm-loop-spin {
  0%, 15% {
    transform: rotate(0deg);
    opacity: 1;
  }
  30% {
    transform: rotate(360deg);
    opacity: 1;
  }
  35%, 100% {
    opacity: 0;
  }
}
@keyframes lm-loop-row {
  0%, 30% {
    max-height: 0;
    opacity: 0;
    transform: translateY(10px);
    padding-top: 0;
    padding-bottom: 0;
  }
  55%, 85% {
    max-height: 40px;
    opacity: 1;
    transform: translateY(0);
    padding-top: 12px;
    padding-bottom: 12px;
  }
  100% {
    max-height: 0;
    opacity: 0;
    transform: translateY(10px);
    padding-top: 0;
    padding-bottom: 0;
  }
}
@media (prefers-reduced-motion: reduce) {
  .lm-row--pending, .lm-btn__icon {
    transition: none;
    animation: none;
  }
  .lm-list.has-loaded .lm-row--pending {
    opacity: 1;
    transform: none;
  }
}

(function () {
  var list = document.querySelector('.lm-list');
  var btn = list.querySelector('.lm-btn');
  btn.addEventListener('click', function () {
    if (list.classList.contains('has-loaded')) return;
    list.classList.remove('is-demo');
    list.classList.add('is-loading');
    setTimeout(function () {
      list.classList.remove('is-loading');
      list.classList.add('has-loaded');
      btn.querySelector('.lm-btn__label').textContent = 'Không còn mục nào';
      btn.disabled = true;
    }, 500);
  });
})();

import { useState, type CSSProperties } from "react";
import styles from "./LoadMoreButton.module.scss";

export type LoadMoreButtonProps = {
  initial: string[];
  more: string[];
  /** 새 행이 밀려 올라오는 시간 (기본 600ms) */
  duration?: number;
  easing?: string;
  /** 브랜드 컬러 */
  color?: string;
};

type Vars = CSSProperties & { "--duration"?: string; "--easing"?: string; "--color"?: string };

/** 더보기 클릭 → 로딩 스피너 → 대기 행이 stagger 로 펼쳐진다 */
export default function LoadMoreButton({
  initial,
  more,
  duration = 600,
  easing = "cubic-bezier(.2,.8,.2,1)",
  color = "#2f6df6",
}: LoadMoreButtonProps) {
  const [loading, setLoading] = useState(false);
  const [loaded, setLoaded] = useState(false);
  const vars: Vars = { "--duration": `${duration}ms`, "--easing": easing, "--color": color };

  const click = () => {
    if (loaded) return;
    setLoading(true);
    setTimeout(() => { setLoading(false); setLoaded(true); }, 500);
  };

  return (
    <div className={styles.list} style={vars}>
      <ul className={styles.rows}>
        {initial.map((t) => <li key={t} className={styles.row}>{t}</li>)}
        {more.map((t, i) => (
          <li key={t} className={`${styles.row} ${styles.pending} ${loaded ? styles.shown : ""}`} style={{ transitionDelay: `${i * 90}ms` }}>{t}</li>
        ))}
      </ul>
      <button className={styles.btn} type="button" onClick={click} disabled={loaded}>
        <svg className={`${styles.icon} ${loading ? styles.spin : ""}`} viewBox="0 0 256 256" aria-hidden="true">
          <g fill="currentColor"><path d="M216 128a88 88 0 1 1-88-88a88 88 0 0 1 88 88" opacity=".2" /><path d="M240 56v48a8 8 0 0 1-8 8h-48a8 8 0 0 1 0-16h27.4l-26.59-24.36l-.25-.24a80 80 0 1 0-1.67 114.78a8 8 0 0 1 11 11.63A95.44 95.44 0 0 1 128 224h-1.32a96 96 0 1 1 69.07-164L224 85.8V56a8 8 0 1 1 16 0" /></g>
        </svg>
        <span>{loaded ? "더 이상 없음" : "더보기"}</span>
      </button>
    </div>
  );
}