in-order BTree traversal in typescript with generators

btree.ts

// binary tree

interface INode {
  left: INode | null;
  value: number;
  right: INode | null;
}

class BinaryTree {
  public root: INode;

  constructor(value: number) {
    this.root = this.newTreeNode(value);
  }

  private newTreeNode(value: number): INode {
    return { value, left: null, right: null };
  }

  insert(value: number, node = this.root): INode {
    if (node === null) return this.newTreeNode(value);

    if (value < node.value) {
      node.left = this.insert(value, node.left);
    } else {
      node.right = this.insert(value, node.right);
    }

    return node;
  }

  *inOrderTraverse(node = this.root): IterableIterator<INode> {
    if (node.left != null) yield* this.inOrderTraverse(node.left);
    yield node;
    if (node.right != null) yield* this.inOrderTraverse(node.right);
  }
}

const tree = new BinaryTree(10);
tree.insert(5);
tree.insert(4);
tree.insert(6);
tree.insert(11);

console.log([...tree.inOrderTraverse()].map(node => node.value).join(', '));