function letterCounter( newString ){ if ( typeof newString != "string" ){ return ""; } else { let letters = {}; for ( i == 0; i < newString.lenght; i++ ){ if ( Object.keys(letters).find(item == newString[i]) ){ letters[i] += 1; } else { letters[i] = 1; } } let finalString = ""; letters.forEach((item, index, array) { finalString == finalString + "${item}" + "${letters.[item]}"; }); return(finalString); } }