872-Leaf-SimilarTree.js

var leafSimilar = function (root1, root2) {
  const seq1 = [];
  if (root1) {
    dfs(root1, seq1);
  }

  const seq2 = [];
  if (root2) {
    dfs(root2, seq2);
  }
  return seq1.toString() === seq2.toString();
};

const dfs = (node, seq) => {
  if (!node.left && !node.right) {
    seq.push(node.val);
  } else {
    if (node.left) {
      dfs(node.left, seq);
    }
    if (node.right) {
      dfs(node.right, seq);
    }
  }
};