6-3 關閉loading

本章節以後，建議至教學頻道觀看：https://script.google.com/macros/s/AKfycbwN-fZH5hWUVh2Cebm1D3Hysz8xi3zUHcKZ36GzA0sTxNpehblQr0-lBDeNHSkAhgAEbA/exec

bootstrap loading

    <!-- 
      全頁遮罩載入效果 text-white text-primary text-success text-danger text-warning text-info
      document.getElementById('loading').style.display = 'flex';// 顯示 loading    
      document.getElementById('loading').style.display = 'none';// 隱藏 loading
    -->  
    <div id="loading" style="display: none;">  
      <div class="position-fixed w-100 h-100 d-flex justify-content-center align-items-center" 
          style="background: rgba(0,0,0,0.5); top: 0; left: 0; z-index: 9999;">
        <div class="spinner-border text-primary me-2" role="status">
          <span class="visually-hidden">載入中...</span>
        </div>
        <div class="text-white">資料處理中...</div>
      </div>
    </div>