BST.js

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

Node.prototype.getData = function(){
  return this.data;
};

var BST = function(){
  this.root = null;
};

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

BST.prototype.inOrder = function( node ){
  if(node){
    this.inOrder(node.left);
    console.log(node.getData());
    this.inOrder(node.right);
  }
};

BST.prototype.preOrder = function( node ){
  if (node) {
    console.log(node.getData());
    this.preOrder(node.left);
    this.preOrder(node.right);
  }
};

BST.prototype.postOrder = function( node ){
  if (node) {
    this.postOrder(node.left);
    this.postOrder(node.right);
    console.log(node.getData());
  }
};

BST.prototype.getMin = function(){
  var current = this.root;
  while(current.left) {
    current = current.left;
  }
  return current.getData();
};

var nums = new BST();
nums.insert(39);
nums.insert(19);
nums.insert(12);
nums.insert(21);
nums.insert(10);
nums.insert(20);
nums.insert(9);