Find K-th Smallest Pair Distance LeetCode solution in JavaScript

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var smallestDistancePair = function (nums, k) {
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  nums.sort((a, b) => a - b);
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  let left = 0,
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    right = nums[nums.length - 1] - nums[0],
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    mid = null,
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    total = 0;
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  while (left < right) {
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    mid = left + Math.floor((right - left) / 2);
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    total = 0;
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    for (var i = 0, j = 1; i < nums.length - 1 && total <= k; i++) {
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      for (; j < nums.length && nums[j] - nums[i] <= mid; j++) {}
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      total += j - i - 1;
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    }
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    if (total >= k) {
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      right = mid;
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    } else {
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      left = mid + 1;
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    }
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  }
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  return left;
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};