diff --git a/src/TreeNode.ts b/src/TreeNode.ts
index 3a8afea4..b7bb64c0 100755
--- a/src/TreeNode.ts
+++ b/src/TreeNode.ts
@@ -1,7 +1,10 @@
+import { Indexer, IndexerL2R } from "./IAdapter";
+
+export type NodeCallback<T> = (node: TreeNode<T>) => void;
 export class TreeNode<T> {
     private _parent: TreeNode<T> | undefined;
     private _children: Array<TreeNode<T>> | undefined;
-    public name: string ;
+    public name: string;
     public data: T | undefined;
 
     public constructor(data: T | undefined = undefined, parent: TreeNode<T> | undefined = undefined, name: string) {
@@ -155,9 +158,28 @@ export class TreeNode<T> {
     }
     public repeatString(target: string, n: number): string {
         let total: string = "";
-        for(let i = 0; i < n; i++){
+        for (let i = 0; i < n; i++) {
             total += target;
         }
         return total;
     }
+    public visit(preOrderFunc: NodeCallback<T> | null = null, postOrderFunc: NodeCallback<T> | null = null, indexFunc: Indexer = IndexerL2R): void {
+        if (preOrderFunc !== null) {
+            preOrderFunc(this);
+        }
+
+        let arr: Array<TreeNode<T>> | undefined = this._children;
+        if (arr !== undefined) {
+            for (let i: number = 0; i < arr.length; i++) {
+                let child: TreeNode<T> | undefined = this.getChildAt(indexFunc(arr.length, i));
+                if(child !== undefined){
+                    child.visit(preOrderFunc, postOrderFunc, indexFunc);
+                }
+            }
+        }
+
+        if (postOrderFunc !== null) {
+            postOrderFunc(this);
+        }
+    }
 }
\ No newline at end of file
diff --git a/src/index.ts b/src/index.ts
index af615d05..895b7142 100755
--- a/src/index.ts
+++ b/src/index.ts
@@ -41,17 +41,9 @@ class TreeNodeTest {
 }
 
 let root: NumberNode = TreeNodeTest.createTree();
-let iter: IEnumberator<TreeNode<number>>;
-let current: TreeNode<number> | undefined = undefined;
 
-iter = new NodeT2BEnumberator(root, IndexerR2L, Stack);
-
-while (iter.moveNext()) {
-    current = iter.current;
-    if (current !== undefined) {
-        console.log(current.repeatString(" ", current.depth * 4) + current.name);
-    }
+function printNodeInfo(node: NumberNode) : void {
+    console.log(node.repeatString(" ", node.depth * 4) + node.name);
 }
 
-// iter = new NodeT2BEnumberator(root, IndexerR2L, Queue);
-// console.log(TreeNodeTest.outputNodesInfo(iter));
\ No newline at end of file
+root.visit(null, printNodeInfo, IndexerR2L);