在前端开发中，我们经常需要处理树形结构的数据。以下是一个基本的JavaScript函数，用于创建和操作树形数据结构：

class TreeNode {  
    constructor(id, parentId, name, children = []) {  
        this.id = id;  
        this.parentId = parentId;  
        this.name = name;  
        this.children = children;  
    }  
  
    // 添加子节点  
    addChildren(node) {  
        this.children.push(node);  
    }  
  
    // 删除子节点  
    deleteChildren(nodeId) {  
        this.children = this.children.filter(child => child.id !== nodeId);  
    }  
}  
  
class Tree {  
    constructor(rootNode) {  
        this.rootNode = rootNode;  
    }  
  
    // 构建树形结构  
    buildTree(nodes) {  
        let tree = [];  
        let map = {};  
        for (let i = 0; i < nodes.length; i++) {  
            let node = nodes[i];  
            map[node.id] = i;  
            if (node.parentId === null || node.parentId === undefined) {  
                tree.push(new TreeNode(node.id, null, node.name, this.buildChildren(nodes, node.id)));  
            } else {  
                nodes[map[node.parentId]].addChildren(new TreeNode(node.id, null, node.name, this.buildChildren(nodes, node.id)));  
            }  
        }  
        return new Tree(tree);  
    }  
  
    // 构建子节点  
    buildChildren(nodes, parentId) {  
        let children = [];  
        for (let i = 0; i < nodes.length; i++) {  
            if (nodes[i].parentId === parentId) {  
                children.push(new TreeNode(nodes[i].id, null, nodes[i].name, this.buildChildren(nodes, nodes[i].id)));  
            }  
        }  
        return children;  
    }  
}