var caesarCipher = function (s, k) {
    let strArr = [];
    for (const ch of s) {
        if (!/^[a-zA-Z]$/.test(ch)) {
            strArr.push(ch);
        } else {
            strArr.push(rotatedChar(ch, k));
        }

    }
    return strArr.join('');
}

function rotatedChar(char, k) {
    let smallLetters = "abcdefghijklmnopqrstuvwxyz"
    let capitalLetters = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
    if (smallLetters.includes(char)) {
        let index = smallLetters.indexOf(char);
        return smallLetters.charAt((index + k) % 26);
    } else {
        let index = capitalLetters.indexOf(char);
        return capitalLetters.charAt((index + k) % 26);
    }
}