cb_letterChanges.js

//Using the JavaScript language, have the function LetterChanges(str) take the str parameter being passed and modify it using the following algorithm. Replace every letter in the string with the letter following it in the alphabet (ie. c becomes d, z becomes a). Then capitalize every vowel in this new string (a, e, i, o, u) and finally return this modified string. 

function LetterChanges(str) { 

  // turn str into an array
  var arr = str.split(""),
      newStr = "";
  
  for (var i in arr){
    if (/[a-yA-Y]/.test(arr[i]))          {arr[i] = String.fromCharCode(arr[i].charCodeAt(0)+1)}
    if (/[aeiou]/.test(arr[i]))           {arr[i] = arr[i].toUpperCase()}
    if (arr[i] === "Z" || arr[i] === "z") {arr[i] = "A"}
  }
  
  newStr = arr.join("");
  return newStr; 
         
}

//My test
var str = "fun times!"
console.log(LetterChanges(str)); //solution: "gvO Ujnft!"


/* Non RegEx Solution

var letterChanges = function(str){
  //function to confirm if myChar is a vowel
  var isVowel = function(myChar){
    var vowel  = ["a","e","i","o","u"],
        result = false;
    for (var i in vowel){
      if(myChar === vowel[i]){
        result = true;
      }
    }
    return result;
  };
  //function that returns the nextLetter (does not handle special cases, see coderbyte code)
  var nextLetter = function(myChar){
    var newCharCode = myChar.charCodeAt(0) + 1
    return myChar.replace(/([a-zA-Z])/, String.fromCharCode(newCharCode))
  };



  //split the input string into an array
  var arr  = str.split(""),
    result = "";
  //evaluate each and convert to next letter
  for (var i in arr){ 
    if (arr[i] !== " "){
      result += nextLetter(arr[i]);
    }else{
      result += " ";
    }
  }
  //review the final and capitalize vowels
  result = result.split("")

  for (var i in result){ 
    if (isVowel(result[i])=== true){
      result.splice(i,1,result[i].toUpperCase())
    }
  }
  str = result.join("");
  return str; 
};

str = "fun times!#";
console.log(letterChanges(str));


*/


/* Prior version, also non RegEx

function LetterChanges(str) { 

  // code goes here 
  //function to confirm if myChar is a vowel
  var isVowel = function(myChar){
    var vowel  = ["a","e","i","o","u"],
        result = false;
    for (var i in vowel){
      if(myChar === vowel[i]){
        result = true;
      }
    }
    return result;
  };
  //function that returns the nextLetter
  var nextLetter = function(myChar){
    return myChar.replace(/([a-zA-Z])[^a-zA-Z]*$/, function(a){
        var c = a.charCodeAt(0);
        switch(c){
            //wraps A after Z and a after z
            case 90: return 'A';
            case 122: return 'a';
            default: return String.fromCharCode(++c);
        }
    });
  }
      
  //split the input string into an array
  var arr  = str.split(""),
    result = "";
  //evaluate each and convert to next letter
  for (var i in arr){ 
    if (arr[i] !== " "){
      result += nextLetter(arr[i]);
    }else{
      result += " ";
    }
  }
  //review the final and capitalize vowels
  result = result.split("")

  for (var i in result){ 
    if (isVowel(result[i])=== true){
      result.splice(i,1,result[i].toUpperCase())
    }
  }
  str = result.join("");
  return str; 
         
}
   
// keep this function call here 
// to see how to enter arguments in JavaScript scroll down
print(LetterChanges(readline()));  
*/

/* Another version w/ Regex

function LetterChanges(str) { 

  // code goes here 
  //filter to check for letter
  var isLetter = function(testChar){
    var alpha = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
    var arr = alpha.split("");
    for (var i in arr){
      if (testChar === arr[i]){
        return true;
      }
    }
    return  false;
  };
  //redo str w/o weird characters
  var strArr = str.split(""),
      finalStr = "",
      newCharCode = 0;
  for (var i in strArr){
    if (isLetter(strArr[i])){
      newCharCode = strArr[i].charCodeAt(0) + 1;
      finalStr += String.fromCharCode(newCharCode);
    }else{
      finalStr += strArr[i];
    }
  }
  //capitalize vowels
  var semi = finalStr.split("");
  var str2 = "";
    for (var i in semi){
      if (semi[i] === "a" || semi[i] === "e" || semi[i] === "i" || semi[i] === "o" || semi[i] === "u"){
        semi[i] = semi[i].toUpperCase();
      }
    }
    str2 = semi.join("");
  return str2;    
}
   
// keep this function call here 
// to see how to enter arguments in JavaScript scroll down
print(LetterChanges(readline()));                            

*/