Palindrome Permutation

palidrome.js

function palindrome(str){
    const unique = [...new Set(str.split(''))];

    const counts = unique.map( char =>{
        return str.match( new RegExp(char, 'g') ).length
    });

    let odd = 0,
        even = 0;

    counts.forEach( count => count % 2 === 0 ? even += 1 : odd += 1 );
    return odd <= 1 && (str.length - odd) / 2 === even;
}