Check if Array Is Sorted and Rotated LeetCode solution in JavaScript

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var check = function (nums) {
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  let decreased = false;
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  for (let i = 1; i < nums.length; i += 1) {
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    if (nums[i] < nums[i - 1]) {
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      if (decreased) {
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        return false;
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      }
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      decreased = true;
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    }
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  }
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  return decreased ? nums[0] >= nums[nums.length - 1] : true;
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};