需限制树形结构子节点最多仅可添加6层级

Alright, let's fix that unlimited node addition issue and cap your tree structure at 6 levels max. The core idea is to calculate how deep the current node is before allowing a child to be added, then block the action if we've hit the limit.

Step 1: Update the AddChild Function #

We'll add logic to count the current node's depth by traversing up the DOM tree. Here's the modified function:

// Add Child
function AddChild(element) {
    // Calculate current depth of the parent node
    let currentDepth = 1;
    let parentElement = element.closest('li');
    
    // Traverse up to count nested levels
    while (parentElement && parentElement.parentElement && parentElement.parentElement.tagName !== 'DIV') {
        if (parentElement.parentElement.tagName === 'UL') {
            currentDepth++;
        }
        parentElement = parentElement.parentElement.parentElement;
    }
    
    // Block addition if we've reached level 6
    if (currentDepth >= 6) {
        alert("Cannot add more than 6 levels of nodes!");
        return;
    }
    
    // Original add logic remains intact
    var ul = element.parentNode.nextElementSibling;
    var li = document.createElement("li");
    domString = '<div class="textbox_cls"> \n\ <span class="caret"></span>\n\ <span class="remove_user" parent_id="1">-</span>\n\ <input type="text" name="username" placeholder="Element">\n\ <span class="add_user" parent_id="1" onclick="AddChild(this);">+</span>\n\ <span class="drag_user">::</span>\n\ </div><ul></ul>';
    li.innerHTML = domString;
    ul.appendChild(li);
    
    // Disable the new node's add button if it would create a 7th level
    const newAddBtn = li.querySelector('.add_user');
    if (currentDepth + 1 >= 6) {
        newAddBtn.classList.add('disabled');
        newAddBtn.onclick = null;
    }
}

Step 2: Add Visual Feedback for Disabled Buttons #

To make it obvious when users can't add more nodes, add this CSS rule to gray out disabled "+" buttons:

.add_user.disabled {
    background: #ccc;
    cursor: not-allowed;
}

Full Updated Code #

Here's the complete working code with all changes included:

HTML + CSS + JavaScript

<html>
<head>
<meta name="viewport" content="width=device-width,initial-scale=1.0">
<style>
input[type='text'] {
  padding: 8px 10px;
  border: 1px solid #e5e5e5;
  color: gray;
  border-radius: 4px;
  font-size: 16px;
}
.add_user {
  background: green;
  color: #fff;
  margin: 4px 0px 4px 5px;
  cursor: pointer;
}
.add_user.disabled {
  background: #ccc;
  cursor: not-allowed;
}
.remove_user {
  background: red;
  color: #fff;
  line-height: 20px !important;
  margin: 4px 5px 4px 0px;
  cursor: pointer;
}
.add_user, .remove_user {
  width: 25px;
  height: 25px;
  display: inline-block;
  text-align: center;
  line-height: 25px;
  border-radius: 50%;
}
.drag_user {
  color: lightgrey;
  line-height: 30px;
  font-weight: bold;
  font-size: 30px;
  letter-spacing: -2px;
  margin: 0px 5px;
  cursor: move;
}
.add_user, .remove_user {
  font-size: 25px;
  font-weight: bold;
}
.User_listing ul {
  margin-bottom: 15px;
  list-style-type: none;
}
.User_listing ul .textbox_cls {
  margin-bottom: 10px;
  display: inline-flex;
  position: relative;
}
.User_listing>ul ul {
  margin-left: 10px;
}
.User_listing>ul li {
  margin: 0;
  padding: 0 0px;
  line-height: 20px;
  color: #369;
  font-weight: bold;
  border-left: 2px dashed rgb(0, 0, 0);
}
.User_listing>ul li:last-child {
  border-left: none;
}
.User_listing>ul li:before {
  position: relative;
  top: -20px;
  height: 30px;
  width: 33px;
  color: white;
  border-bottom: 2px dashed rgb(0, 0, 0);
  content: "";
  display: inline-block;
  left: 0px;
}
.User_listing>ul li:last-child:before {
  border-left: 2px dashed rgb(0, 0, 0);
}
</style>
</head>
<body>
<div class="User_listing">
<ul>
<li>
<div class="textbox_cls" total_ul="1">
<span class="caret"></span>
<span class="remove_user" parent_id="1">-</span>
<input type="text" name="username" placeholder="Element" />
<span class="add_user" parent_id="1" onclick="AddChild(this);">+</span>
<span class="drag_user">::</span>
</div>
<ul>
</ul>
</li>
</ul>
</div>

<script>
// Add Child
function AddChild(element) {
    // Calculate current depth of the parent node
    let currentDepth = 1;
    let parentElement = element.closest('li');
    
    // Traverse up to count nested levels
    while (parentElement && parentElement.parentElement && parentElement.parentElement.tagName !== 'DIV') {
        if (parentElement.parentElement.tagName === 'UL') {
            currentDepth++;
        }
        parentElement = parentElement.parentElement.parentElement;
    }
    
    // Block addition if we've reached level 6
    if (currentDepth >= 6) {
        alert("Cannot add more than 6 levels of nodes!");
        return;
    }
    
    // Original add logic remains intact
    var ul = element.parentNode.nextElementSibling;
    var li = document.createElement("li");
    domString = '<div class="textbox_cls"> \n\ <span class="caret"></span>\n\ <span class="remove_user" parent_id="1">-</span>\n\ <input type="text" name="username" placeholder="Element">\n\ <span class="add_user" parent_id="1" onclick="AddChild(this);">+</span>\n\ <span class="drag_user">::</span>\n\ </div><ul></ul>';
    li.innerHTML = domString;
    ul.appendChild(li);
    
    // Disable the new node's add button if it would create a 7th level
    const newAddBtn = li.querySelector('.add_user');
    if (currentDepth + 1 >= 6) {
        newAddBtn.classList.add('disabled');
        newAddBtn.onclick = null;
    }
}
</script>
</body>
</html>

How It Works #

• Depth Calculation: We traverse up from the clicked "+" button, counting each nested <ul> to determine the current node's level.
• Limit Enforcement: If the current node is already at level 6, we show an alert and stop the add action.
• Visual Feedback: Nodes at level 5 get their "+" button disabled (gray background, no click action) so users can't accidentally try to add a 7th level.

内容的提问来源于stack exchange，提问作者Hardik Kalathiya