Largest Number After Digit Swaps by Parity LeetCode solution in JavaScript

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/**
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 * @param {number} num
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 * @return {number}
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 */
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var largestInteger = function (num) {
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  var nums = num.toString().split(""); //splitting the numbers into an array
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  var odd = []; //helps keep a track of odd numbers
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  var even = []; //helps keep a track of even numbers
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  for (var i = 0; i < nums.length; i++) {
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    if (nums[i] % 2 === 0)
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      //pushing even numbers to even array
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      even.push(nums[i]); //pushing odd numbers to odd array
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    else odd.push(nums[i]);
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  }
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  odd.sort((a, b) => a - b); //sorting the arrays in ascending order
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  even.sort((a, b) => a - b);
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  var ans = [];
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  for (var i = 0; i < nums.length; i++) {
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    if (nums[i] % 2 === 0) {
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      //replacing even with even
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      ans.push(even[even.length - 1]); //pushing the greatest even number in the ans
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      even.pop(); //popping the used number
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    } else {
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      //replacing odd with odd
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      ans.push(odd[odd.length - 1]); //pushing the greatest odd number in the ans
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      odd.pop(); //popping the used number
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    }
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  }
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  var ans2 = parseInt(ans.join("")); //converting the ans array into an int number
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  return ans2;
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};