Elimination Game LeetCode solution in JavaScript

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var lastRemaining = function (n) {
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  let sum = 1;
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  let num = 1;
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  let bool = true;
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  while (n > 1) {
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    if (bool) {
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      sum += num;
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      bool = false;
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    } else {
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      if (n % 2) {
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        sum += num;
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      }
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      bool = true;
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    }
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    num *= 2;
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    n = Math.floor(n / 2);
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  }
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  return sum;
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};