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HTML 

              
                
<body>
<div class="change-img">
  <div class="change-img__main js-change-img-main">
    <img src="https://images.unsplash.com/photo-1734426668495-670bba0a8d79?crop=entropy&cs=srgb&fm=jpg&ixid=M3wzMjM4NDZ8MHwxfHJhbmRvbXx8fHx8fHx8fDE3Mzc2NjU0MDJ8&ixlib=rb-4.0.3&q=8" alt="キャストの画像" />
  </div>
  <div class="change-img__img-sub">
    <ul class="change-img__list">
      <button class="change-img__item js-change-img-button">
        <img src="https://images.unsplash.com/photo-1734426668495-670bba0a8d79?crop=entropy&cs=srgb&fm=jpg&ixid=M3wzMjM4NDZ8MHwxfHJhbmRvbXx8fHx8fHx8fDE3Mzc2NjU0MDJ8&ixlib=rb-4.0.3&q=8" alt="キャストのサブ画像" />
      </button>
      <button class="change-img__item js-change-img-button">
        <img src="https://images.unsplash.com/photo-1735669356374-8ea7506cd1d2?crop=entropy&cs=srgb&fm=jpg&ixid=M3wzMjM4NDZ8MHwxfHJhbmRvbXx8fHx8fHx8fDE3Mzc2NjU0MDJ8&ixlib=rb-4.0.3&q=85" alt="キャストのサブ画像" />
      </button>
      <button class="change-img__item js-change-img-button">
        <img src="https://images.unsplash.com/photo-1737047938856-ea38cdb28dea?crop=entropy&cs=srgb&fm=jpg&ixid=M3wzMjM4NDZ8MHwxfHJhbmRvbXx8fHx8fHx8fDE3Mzc2NjU0MDJ8&ixlib=rb-4.0.3&q=85" alt="キャストのサブ画像" />
      </button>
        <button class="change-img__item js-change-img-button">
        <img src="https://images.unsplash.com/photo-1737047938856-ea38cdb28dea?crop=entropy&cs=srgb&fm=jpg&ixid=M3wzMjM4NDZ8MHwxfHJhbmRvbXx8fHx8fHx8fDE3Mzc2NjU0MDJ8&ixlib=rb-4.0.3&q=85" alt="キャストのサブ画像" />
      </button>
    </ul>
  </div>
</div>
</body>
!

CSS 

              
                body {
  font-family: Arial, sans-serif;
  margin: 0;
  padding: 0;
}

.change-img {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 20px;
  padding: 20px;
  max-width: 300px;
  margin: 0 auto; 

}

.change-img__main {
  width: 100%;
  text-align: center;
}

.change-img__main img {
  aspect-ratio: 2/1;
  width: 100%;
  height: auto;
  border-radius: 8px;
  object-fit: cover;
}

.change-img__img-sub {
  width: 100%;
}

.change-img__list {
    width: 100%;
  display: flex;
  gap: 10px;
  list-style: none;
  padding: 0;
  margin: 0;
overflow-x: scroll;
}

.change-img__item {
  background: none;
  border: none;
  padding: 0;
  cursor: pointer;
  min-width: 80px;
}

.change-img__item img {
  aspect-ratio: 1;
  width: 100%;
  object-fit: cover;
  border-radius: 4px;
}
!

JS 

              
                // メイン画像を取得
const $mainImage = $('.js-change-img-main img');
// サブ画像ボタンをすべて取得
const $buttons = $('.js-change-img-button');

// 各ボタンにクリックイベントを追加
$buttons.on('click', function() {
  // ボタン内の画像要素を取得
  const newImageSrc = $(this).find('img').attr('src');
  // メイン画像のsrcを更新
  $mainImage.attr('src', newImageSrc);
});
!
999px

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