Beautiful Arrangement II LeetCode solution in JavaScript

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var constructArray = function (n, k) {
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  const result = [];
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  let left = 1;
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  let right = n;
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  for (let index = 0; index < n; index++) {
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    if (k === 1) {
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      result.push(left++);
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      continue;
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    }
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    const num = k & 1 ? left++ : right--;
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    result.push(num);
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    k -= 1;
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  }
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  return result;
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};