How can I create tree table by using AJAX that load 1 level at a time?

To create a tree table using AJAX that loads one level at a time, you can follow these steps:

1. Design the HTML Structure: Design the HTML structure for the tree table. You can use nested <ul> and <li> elements to represent the tree hierarchy. For each tree node, you can have an expansion icon (e.g., a plus sign) to indicate that it can be expanded to load the next level.

htmlCopy code
<div id="treeTable">
  <ul>
    <li class="expandable">
      Node 1
      <ul></ul>
    </li>
    <li class="expandable">
      Node 2
      <ul></ul>
    </li>
    <!-- Add more nodes here -->
  </ul>
</div>

2. Add CSS Styling: Add some CSS styling to make the tree structure look visually appealing and indicate expandable/collapsible nodes.

cssCopy code
/* CSS for tree table */
#treeTable {
  list-style: none;
  padding-left: 20px;
}

#treeTable li.expandable {
  cursor: pointer;
}

#treeTable li.collapsed > ul {
  display: none;
}

#treeTable li.expandable::before {
  content: '+';
  margin-right: 5px;
}

#treeTable li.collapsed::before {
  content: '-';
  margin-right: 5px;
}

3. Implement AJAX Functionality: Write JavaScript code to handle the AJAX functionality for loading the tree levels dynamically. You can use the Fetch API or jQuery AJAX to fetch the data from the server.

javascriptCopy code
document.addEventListener('DOMContentLoaded', function () {
  const treeTable = document.getElementById('treeTable');

  treeTable.addEventListener('click', function (event) {
    const target = event.target;
    if (target.classList.contains('expandable')) {
      // Get the parent <li> element and check if it's collapsed
      const listItem = target;
      if (listItem.classList.contains('collapsed')) {
        // Get the children <ul> element
        const childList = listItem.querySelector('ul');

        // Fetch data for the next level using AJAX (replace 'your_ajax_url' with your actual AJAX endpoint)
        fetch('your_ajax_url')
          .then(response => response.json())
          .then(data => {
            // Create HTML for the next level and append it to the children <ul> element
            let html = '';
            data.forEach(node => {
              html += `<li class="expandable">${node.name}<ul></ul></li>`;
            });
            childList.innerHTML = html;

            // Remove the 'collapsed' class to show the newly loaded children
            listItem.classList.remove('collapsed');
          })
          .catch(error => {
            console.error('Error fetching data:', error);
          });
      } else {
        // If the node is expanded, collapse it
        listItem.classList.add('collapsed');
      }
    }
  });
});

4. Server-Side Implementation: On the server-side, you need to create an API endpoint that returns the data for the next level of the tree when requested by the AJAX call. This can be in JSON format containing the information for the child nodes.

With these steps, your tree table will load one level at a time, and when a user clicks on an expandable node, it will make an AJAX request to the server to fetch the data for the next level. The fetched data will be dynamically added to the tree table, allowing users to progressively explore the tree hierarchy.