Caesar Cipher | DDS Code Challenge

ceaserCipher.js

var __spreadArray = (this && this.__spreadArray) || function (to, from, pack) {
    if (pack || arguments.length === 2) for (var i = 0, l = from.length, ar; i < l; i++) {
        if (ar || !(i in from)) {
            if (!ar) ar = Array.prototype.slice.call(from, 0, i);
            ar[i] = from[i];
        }
    }
    return to.concat(ar || Array.prototype.slice.call(from));
};
function caesarCipher(string, shiftValue) {
    var lettersArray = __spreadArray([], Array(26), true).map(function (_, index) { return String.fromCharCode(97 + index); }); // Lowercase letters a-z
    lettersArray.push.apply(// Lowercase letters a-z
    lettersArray, __spreadArray([], Array(26), true).map(function (_, index) { return String.fromCharCode(65 + index); })); // Uppercase letters A-Z
    // Thanks ChatGPT for the above code.
    var splitString = string.split('');
    var newString = "";
    splitString.forEach(function (char) {
        if (char == ' ')
            return newString += ' ';
        for (var i = 0; i < lettersArray.length; i++) {
            if (char == lettersArray[i]) {
                newString += lettersArray[i + shiftValue];
            }
        }
    });
    return newString;
}

ceaserCipher.ts

function caesarCipher(string: string, shiftValue: number) {
    const lettersArray: string[] = [...Array(26)].map((_, index) => String.fromCharCode(97 + index)); // Lowercase letters a-z
    lettersArray.push(...[...Array(26)].map((_, index) => String.fromCharCode(65 + index))); // Uppercase letters A-Z
    // Thanks ChatGPT for the above code.

    let splitString:string[] = string.split('');
    let newString:string = "";

    splitString.forEach(char => {
        if(char == ' ') return newString += ' ';
        for (let i = 0; i < lettersArray.length; i++) {
            if(char == lettersArray[i]) {
                newString += lettersArray[i + shiftValue];
            }
        }
    });

    return newString;
}