All Elements in Two Binary Search Trees LeetCode solution in JavaScript

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var getAllElements = function (root1, root2) {
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  const ans = [];
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  const traverse = (r) => {
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    if (!r) return;
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    traverse(r.left);
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    ans.push(r.val);
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    traverse(r.right);
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  };
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  traverse(root1);
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  traverse(root2);
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  return ans.sort((a, b) => a - b);
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};