Generate Parentheses LeetCode solution in JavaScript

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var generateParenthesis = function (n) {
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  let ans = [];
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  generate_parenthisis(n, 0, 0, "");
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  return ans;
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  function generate_parenthisis(n, open, close, res) {
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    if (open == n && close == n) {
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      ans.push(res);
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      return;
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    }
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    if (open < n) {
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      generate_parenthisis(n, open + 1, close, res + "(");
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    }
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    if (close < open) {
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      generate_parenthisis(n, open, close + 1, res + ")");
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    }
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  }
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};