Number of Subarrays with Bounded Maximum LeetCode solution in JavaScript

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var numSubarrayBoundedMax = function (nums, left, right) {
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  let ans = 0,
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    low = 0,
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    mid = 0;
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  for (let i = 0; i < nums.length; i++) {
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    let num = nums[i];
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    if (num > right) mid = 0;
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    else ans += ++mid;
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    if (num >= left) low = 0;
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    else ans -= ++low;
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  }
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  return ans;
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};