portugueseHello = function () {
  return "Olá, ";
}

englishHello = function () {
  return "Hello, ";
}

francaisHello = function () {
  return "Bonjour, ";
}

function helloWorld(languageFunction, name) {
  // return `${languageFunction()} ${name}`; utilizando Template Literals do ES6+
  return languageFunction() + name;
}

helloWorld(portugueseHello, "Felix"); // output: Olá, Felix

helloWorld(englishHello, "Felix");    // output: Hello, Felix