License Key Formatting LeetCode solution in JavaScript

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// Please upvote if you like the solution. Thanks
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var licenseKeyFormatting = function (s, k) {
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  let str = s.replace(/[^A-Za-z0-9]/g, "").toUpperCase();
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  let ans = "";
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  let i = str.length;
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  while (i > 0) {
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    ans = "-" + str.substring(i - k, i) + ans; // we are taking k characters from the end of string and adding it to answer
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    i = i - k;
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  }
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  return ans.substring(1); // removing the "-" which is present in the start of ans
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};