Javascript Data Structure Tree Binary Tree Clone

var BinaryTree = function (val) {
  this.val = val;/*from w  w w. j a  va2s  . com*/
  this.left = null;
  this.right = null;
};

BinaryTree.prototype.insert = function (val) {
  if (val === this.val) {
    return;
  } else if (val <= this.val) {
    if (this.left === null) {
      this.left = new BinaryTree(val);
    } else {
      this.left.insert(val);
    }
  } else {
    if (this.right === null) {
      this.right = new BinaryTree(val);
    } else {
      this.right.insert(val);
    }
  }
};

BinaryTree.prototype.clone = function () {
  var clonedTree = new BinaryTree(this.val);

  if (this.left) {
    clonedTree.left = this.left.clone();
  }

  if (this.right) {
    clonedTree.right = this.right.clone();
  }

  return clonedTree;
};

var test1 = new BinaryTree(15)
test1.insert(7);
test1.insert(22);
test1.insert(12);
test1.insert(5);
test1.insert(50);
test1.insert(17);

var cloned = test1.clone();

console.log('cloned:', cloned, '\noriginal:', test1);