Binary Search Tree

Binary-Search-Tree.js

function BinarySearchTree() {

  function Node(key) {
    this.key = key;
    this.left = null;
    this.right = null;
  }

  let root = null;

  var insertNode = function (node, newNode) {
    if (newNode.key < node.key) {
      if (node.left === null) node.left = newNode;
      else insertNode(node.left, newNode);
    } else {
      if (node.right === null) node.right = newNode;
      else insertNode(node.right, newNode);
    }
  }

  this.insert = function (key) {
    const newNode = new Node(key);
    if (root === null) {
      root = newNode;
    } else {
      insertNode(root, newNode);
    }
  }

  var inOrderTraversal = function (node) {
    if (node.left) inOrderTraversal(node.left);
    console.log(node.key);
    if (node.right) inOrderTraversal(node.right);
  }
  this.inOrderTraversal = function () {
    if (root) inOrderTraversal(root);
  }

  var preOrderTraversalNode = function (node) {
    console.log(node.key);
    if (node.left) preOrderTraversalNode(node.left);
    if (node.right) preOrderTraversalNode(node.right);
  }
  this.preOrderTraversal = function () {
    if (root) preOrderTraversalNode(root);
  }

  var postOrderTraversalNode = function (node) {
    if (node.left) postOrderTraversalNode(node.left);
    if (node.right) postOrderTraversalNode(node.right);
    console.log(node.key);
  }
  this.postOrderTraversal = function () {
    if (root) postOrderTraversalNode(root);
  }
}

var bst = new BinarySearchTree();
bst.insert(4);
bst.insert(7);
bst.insert(2);
bst.insert(3);
bst.insert(1);
bst.insert(8);
//    4 
//   / \
//  2   7
// / \   \
//1   3   8
bst.inOrderTraversal();
console.log('---');
bst.preOrderTraversal();
console.log('---');
bst.postOrderTraversal();