Pour convertir un Number

oups j'ai encore une autre question :)

Pour le restart j'ai cherché sur mdn, ca à l'air de bien fonctionner sauf que j'ai une alert() en debut de mon code avec un message d'accueil, j'ai essayé avec un if else statement d'afficher plutot "Hello again" si l'utilisateur souhaite recommencer a calculer, sauf que "Hello again" s'affiche mais aussi le message d'accueil.

Si vous avez des idées afin d'optimiser ca, merci :)

Je vais continuer à chercher de mon coté.

// Global variable
let questionCalc;
let firstNumber;
let secondNumber;
let result;
let restart;

// Bloc function
function add(firstNumber, secondNumber) {
  let result = firstNumber + secondNumber;
  return result;
}

function multiply(firstNumber, secondNumber) {
  let result = firstNumber * secondNumber;
  return result;
}

function substraction(firstNumber, secondNumber) {
  let result = firstNumber - secondNumber;
  return result;
}

function divide(firstNumber, secondNumber) {
  let result = firstNumber / secondNumber;
  if (secondNumber == 0) {
    throw new Error(`Cannot divide ${secondNumber} by 0.`);
  } else {
    return result;
  }
}
if (!restart) {
  alert("Hooray 👾 ! Welcome to the magical world of numbers and operations!");
}

// message welcome

// Bloc do while
do {
  questionCalc = +prompt(
    `What would you like to do?
     1 🟡 Addition
     2 🟢 Multiplication
     3 🟣 Subtraction
     4 🟠 Division`
  );
} while (![1, 2, 3, 4].includes(questionCalc));

do {
  firstNumber = +prompt("Choose a first number 🦒");
  secondNumber = +prompt("Choose a second number 🐧");
} while (isNaN(firstNumber) || isNaN(secondNumber));

// switch
try {
  switch (questionCalc) {
    case 1:
      result = add(firstNumber, secondNumber);
      break;

    case 2:
      result = multiply(firstNumber, secondNumber);
      break;

    case 3:
      result = substraction(firstNumber, secondNumber);
      break;

    case 4:
      result = divide(firstNumber, secondNumber);
      break;

    default:
      throw new Error(`An error has occurred 🔥`);
  }
  alert(`The result is : ${result} 🐼`);
} catch (error) {
  alert(error);
}

restart = confirm("Do you like try again 🙉?");
if (restart) {
  window.location.reload();
  alert("Hello again 😀");
} else {
  alert("Bye bye See you again! 🦊");
}
// end