text: (function() {
      var summaryTextArea = document.querySelector('.summaryTextArea');
      var switchPreview = document.getElementById('switchPreview');
      var preview = document.getElementById('preview');
  
      var isPreviewMode = false;
  
      preview.style.display = 'none';
  
      switchPreview.addEventListener('click', function() {
          isPreviewMode = !isPreviewMode;
  
          if (isPreviewMode) {
              MarkdownUtil.render({
                  src: '.summaryTextArea',
                  to: '#preview'
              });
  
              preview.style.display = 'block';
              summaryTextArea.style.display = 'none';
              switchPreview.textContent = '編集';
          } else {
              preview.style.display = 'none';
              summaryTextArea.style.display = 'block';
              switchPreview.textContent = 'プレビュー';
          }
      });
  })();
  