Combinations LeetCode solution in JavaScript

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var combine = function (n, k) {
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  function helper(start, end, combo, subset, answer) {
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    if (combo == 0) {
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      answer.push([...subset]);
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      return;
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    }
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    if (end - start + 1 < combo) {
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      return;
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    }
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    if (start > end) {
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      return;
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    }
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    subset.push(start);
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    helper(start + 1, end, combo - 1, subset, answer);
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    subset.pop();
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    helper(start + 1, end, combo, subset, answer);
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  }
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  const answer = [];
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  helper(1, n, k, [], answer);
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  return answer;
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};