这个获取树路径的函数哪里有问题呢？

构造了一个父子树，想获取某个节点的路径，可是获取不了，不知道哪里出错，求解。

var data = [{
    'id': 'root',
    'text': 'Root',
    'children': [{
        'id': 1,
        'text': 'Child 1'
    }, {
        'id': 2,
        'text': 'Child 2',
        'children': [{
            'id': 6,
            'text': 'Child 6'
        }, {
            'id': 7,
            'text': 'Child 5',
            'children': [

            ]
        }]
    }]
}];
var tree = function(data) {
    this.data = data;
}
tree.prototype = {
    init: function(tree, nodeParent) {
        var _this = this;
        tree = tree || this.data;
        if (tree && Array.isArray(tree)) {
            tree.forEach(function(node, index) {
                node.parent = nodeParent;
                if (node.children && Array.isArray(node.children)) {
                    _this.init(node.children, node);
                }
            })
        }
    },
    get_path: function(node, path) {
        path = path || "";
        if (node.parent) {
            path = node.text + ' >> ' + path;
            this.get_path(node.parent, path);
        } else {
            return path;
        }
        console.log(path); // Child 2 >> Child 6 >>
    },
    // 遍历树
    traverse: function(tree, fn) {
        var _this = this;
        tree = tree || this.data;

        if (tree && Array.isArray(tree)) {
            tree.forEach(function(node, index) {
                fn && fn.call(_this, node, tree, index);
                if (node && node.children && Array.isArray(node.children)) {
                    _this.traverse(node.children, fn);
                }
            })
        } else {
            fn.call(_this, tree);
        }
    },
    _get: function(id, fn) {
        var _this = this;
        var found = false;
        this.traverse(this.tree, function(node, tree, index) {
            if (node.id === id) {
                found = node;
                fn && fn.call(_this, node, tree, index);
            }
        })

        if (!found) {
            throw new Error("can get node id " + id);
        }
        return found;
    },
};

var mytree = new tree(data);
mytree.init();

console.log(mytree.get_path(mytree._get(6)));

---

使用上面的get_path递归方法，最后root节点的引用失效了（可能是有Circular相互引用导致），下面的函数有效。

    get_path: function(node, path) {
        console.log(node);
        console.log("-".repeat(10));
        path = path || "";                        
        while(node.parent) {
            path = node.text +' >> ' + path;
            node = node.parent;
        }
        path = node.text +' >> ' + path; // ROOT
        return path;
    },

或许应该避免循环引用,只保留父节点的id,获取路径。（效率不高）

    init: function(tree, nodeParent) {
        var _this = this;
        tree = tree || this.data;
        if (tree && Array.isArray(tree)) {
            tree.forEach(function(node, index) {
                node.parent = nodeParent && nodeParent.id ? nodeParent.id ： undefined;
                if (node.children && Array.isArray(node.children)) {
                    _this.init(node.children, node);
                }
            })
        }
    },
    get_path: function(node) {
        path = [], parent;            
        while(node.parent) {
            parent = this._get(node.parent);
            path.push(parent);
            node = parent;
        }
        return path.reverse();
    },