Couls someone please take a quick look at this attempt at a function and see if they can find any problems with it:
{
var resultString;
resultString = ";

for (var position = 0; position < aString.length; position = position + 1)
{
if isVowel(aString.charAt(position))
{
resultString = aString.charAt(position) + aString.charAt(position) + resultString
}
else
{
resultString = aString.chatAt(position) + resultSTring
}
};
return resultString
}

Umm ... what do you want it to do?