Flip Equivalent Binary Trees LeetCode solution in JavaScript

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var flipEquiv = function (root1, root2) {
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  const flipEquivHelper = (r1 = root1, r2 = root2) => {
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    if (!r1 && !r2) return true;
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    if (!r1 || !r2) return false;
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    if (r1.val != r2.val) return false;
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    let ans = false;
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    // normal
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    ans =
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      ans ||
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      (flipEquivHelper(r1.left, r2.left) &&
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        flipEquivHelper(r1.right, r2.right));
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    // flip
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    ans =
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      ans ||
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      (flipEquivHelper(r1.right, r2.left) &&
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        flipEquivHelper(r1.left, r2.right));
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    return ans;
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  };
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  return flipEquivHelper();
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};