javascript实现二叉树遍历的代码

function Node(data, left, right) {
  this.data = data;
  this.left = left;
  this.right = right;
  this.show = show;
}
function show() {
  return this.data;
}

function BST() {
  this.root = null;
  this.insert = insert;
}
function insert(data) {
  var n = new Node(data, null, null);
  if (this.root == null) {
   this.root = n;
  }
  else {
   var current = this.root;
   var parent;
   while (true) {
     parent = current;
     if (data < current.data) {
      current = current.left;
      if (current == null) {
        parent.left = n;
        break;
      }
     }
     else {
      current = current.right;
      if (current == null) {
        parent.right = n;
        break;
      }
     }
   }
  }
}

function preOrder(node) {
  if (!(node == null)) {
   console.log(node.show() + " ");
   preOrder(node.left);
   preOrder(node.right);
  }
}

// 给BST类添加先序遍历的成员方法
function BST() {
  this.root = null;
  this.insert = insert;
  this.preOrder = preOrder;
}

var bst = new BST();
var nums = [10, 3, 18, 2, 4, 13, 21, 9, 8, 9];
for(var i = 0; i < nums.length; i++) {
  bst.insert(nums[i]);
}
bst.preOrder(bst.root);

function inOrder(node) {
  if (!(node == null)) {
   inOrder(node.left);
   console.log(node.show() + " ");
   inOrder(node.right);
  }
}

// 给BST类添加该成员方法
function BST() {
  this.root = null;
  this.insert = insert;
  this.preOrder = preOrder;
  this.inOrder = inOrder;
}

function postOrder(node) {
  if (!(node == null)) {
   postOrder(node.left);
   postOrder(node.right);
   console.log(node.show() + " ");
  }
}

// 给BST类添加该成员方法
function BST() {
  this.root = null;
  this.insert = insert;
  this.preOrder = preOrder;
  this.inOrder = inOrder;
  this.postOrder = postOrder;
}