function crypt(input) {
    var output = [];
    var charCode;
    for (var i = 0; i < input.length; i++) {
        charCode = input.charCodeAt(i) ^ key[i % key.length].charCodeAt(0);

    output.push(String.fromCharCode(charCode));
    }
    return output.join("");
}

const key = 'randomeky';

const encryted = crypt('raz dwa trzy', key);
console.log('encrypted', encryted);
const decrypted = crypt(encryted, key);
console.log('decrypted', decrypted);