Function dfs

javascript/0102-binary-tree-level-order-traversal.js:53–58

(root, level, levels)

};

const dfs = (root, level, levels) => {
    if (root.left) levelOrder(root.left, level + 1, levels);
    if (root.right) levelOrder(root.right, level + 1, levels);

    return levels;
};