isPalindromePermutation.js

function isPalindromePermutation(string) {
    let counter = 0;

    for (let i = 0; i < string.length; i++) {
        const char = string[i];
        if (char === ' ') {
            continue;
        }

        const charCodeNormalized = char.toLowerCase().charCodeAt(0) - 'a'.charCodeAt(0);
        if (charCodeNormalized < 0 || charCodeNormalized > 25) {
            throw new Error('Unexpected non English alphabet character: ' + char);
        }

        counter ^= 1 << charCodeNormalized;
    }

    return (counter & (counter - 1)) === 0;
};