Combination Sum LeetCode solution in JavaScript

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function recursion(index, list, target, res, arr) {
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  if (index == arr.length) {
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    if (target == 0) {
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      res.push([...list]);
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    }
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    return;
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  }
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  if (arr[index] <= target) {
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    list.push(arr[index]);
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    recursion(index, list, target - arr[index], res, arr);
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    list.pop();
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  }
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  recursion(index + 1, list, target, res, arr);
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}
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var combinationSum = function (candidates, target) {
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  let res = [];
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  recursion(0, [], target, res, candidates);
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  return res;
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};