How to check if a permutation is a palindrome in JavaScript

JavaScript, algorithms, strings

Here is one way to determine if a permutation is a palindrome in JavaScript.
Time complexity: O(n)
Space complexity: O(1)

permutationPalindromeTry in REPL
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function palindromePermutation(string) {
  const unpaired = string
                  .toLowerCase()
                  .split('')
                  .reduce((set, char) => {
                    if (char !== ' ') {
                      (set.has(char) && set.delete(char)) || set.add(char)
                    }
                    return set;
                  }, new Set());
                  
  return unpaired.size <= 1;                
}

Test cases can be found at REPL.it