Leaf-Similar Trees LeetCode solution in JavaScript

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/*
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 * Definition for a binary tree node.
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 * function TreeNode(val, left, right) {
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 *     this.val = (val===undefined ? 0 : val)
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 *     this.left = (left===undefined ? null : left)
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 *     this.right = (right===undefined ? null : right)
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 * }
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 */
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/**
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 * @param {TreeNode} root1
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 * @param {TreeNode} root2
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 * @return {boolean}
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 */
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var leafSimilar = function (root1, root2) {
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  let array1 = [],
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    array2 = [];
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  let leaf1 = getLeaf(root1, array1),
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    leaf2 = getLeaf(root2, array2);
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  if (leaf1.length !== leaf2.length) {
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    // if different lengths, return false right away
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    return false;
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  }
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  for (let i = 0; i < leaf1.length; i++) {
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    if (leaf1[i] !== leaf2[i]) {
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      // compare pair by pair
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      return false;
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    }
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  }
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  return true;
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};
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var getLeaf = function (root, array) {
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  // DFS
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  if (!root) {
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    return;
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  }
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  if (!(root.left || root.right)) {
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    array.push(root.val); // push leaf value to the array
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  }
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  getLeaf(root.left, array);
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  getLeaf(root.right, array);
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  return array;
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};