// JavaScript 实现二叉树

function BinaryTree ()

{

  var Node = function (key)

  {

    this.key = key;

    this.left = null;

    this.right = null;

  }

  var root = null;

  var insertNode = function (Node, newNode)

  {

    if (newNode.key < node.key) {

      if (node.left === null) {

        if (node.left === null) {

          node.left = newNode;

        } else {

          insertNode(node.left, newNode);

        }

      } else {

        if (node.right === null) {

          node.right = newNode;

        } else {

          insertNode(node.left, newNode);

        }

      } else {

        if (node.right === null) {

          node.right = newNode;

        } else {

          insertNode(node.right, newNode);

        }

      }

    }

    this.insert = function (key)

    {

      var newNode = new Node(key);

      if (root === null) {

        root = node;

      } else {

        insertNode(root, newNode);

      }

    }

    // 中序遍历

    var inOrderTraverseNode = function (node, callback)

    {

      if (node !== null) {

        inOrderTraverseNode(node.left, callback);

        callback(node.key);

        inOrderTraverseNode(node.right, callback);

      }

    }

    this.inOrderTraverse = function (callback)

    {

      inOrderTraverseNode(root, callback);

    }

  }

}

var nodes = [8, 3, 10, 1, 6, 14, 4, 7, 13];

var binaryTree = new BinaryTree();

nodes.forEach (function (key))

{

  binaryTree.insert(key);

}

var callback = function (key)

{

  console.log(key);

}

binaryTree.inOrderTraverse(callback);