Every budding hacker needs an alias! The Phantom Phreak, Acid Burn, Zero Cool and Crash Override are some notable examples from the film Hackers.

Your task is to create a function that, given a proper first and last name, will return the correct alias.

• Two objects that return a one word name in response to the first letter of the first name and one for the first letter of the surname are already given.

• If the first character of either of the names given to the function is not a letter from A - Z, you should return "Your name must start with a letter from A - Z."

• Sometimes people might forget to capitalize the first letter of their name so your function should accommodate for these grammatical errors.

var firstName = {A: 'Alpha', B: 'Beta', C: 'Cache' ...}
var surname = {A: 'Analogue', B: 'Bomb', C: 'Catalyst' ...}

aliasGen('Larry', 'Brentwood') === 'Logic Bomb'
aliasGen('123abc', 'Petrovic') === 'Your name must start with a letter from A - Z.'

https://www.codewars.com/kata/578c1e2edaa01a9a02000b7f

const initialCap = (str) => str[0].toUpperCase();
const isValidName = (name) => /^[a-z]/i.test(name);
const aliasGen = (fName, lName) => {
  return (isValidName(fName) && isValidName(lName))
    ? `${ firstName[initialCap(fName)] } ${ surname[initialCap(lName)] }`
    : 'Your name must start with a letter from A - Z.';
}

//

function aliasGen(fname, lname) {
    let output = "";
  
    // transformar tudo em maiuscula
    fname = fname.toUpperCase();
    lname = lname.toUpperCase();
  
    // pegar primeira letra do nome
    let firstLetter = fname[0];
  
    // pegar primeira letra do sobrenome
    let secondLetter = lname[0];
  
    let regexTest = new RegExp('[A-Z]');
  
    // se alguma delas não for letra [A-Z], retornar erro
    if (
      ! regexTest.test(firstLetter)
      ||
      ! regexTest.test(secondLetter)
    ) {
      return "Your name must start with a letter from A - Z.";
    }
    
    // busco nos objetos e monto nova string
    output = `${firstName[firstLetter]} ${surname[secondLetter]}`;
    
  // retorno a string  
  return output;
}

//

function aliasGen(first, last) {
  if('0123456789'.indexOf(first[0]) != -1 || '0123456789'.indexOf(last[0]) != -1) {
    return 'Your name must start with a letter from A - Z.';
  }
  first = first.toUpperCase();
  last = last.toUpperCase();
  return firstName[first[0]] + ' ' + surname[last[0]];
}

//

function aliasGen(first, last){
    if (first[0].match(/[A-Z]/gi) && last[0].match(/[A-Z]/gi)) {
      return firstName[first[0].toUpperCase()] + ' ' + surname[last[0].toUpperCase()]
    } else {
      return 'Your name must start with a letter from A - Z.'
    }
}