Beginner Question - Prompts , variables and scopes

Question

I am trying to make a global scoped variable which stores a prompt value (player's name) but only fire when I click on the Start button.(This is why the variable is not declared outside the function Start)

How can I make this variable value (the name of the player) accessible to other functions, but only call the prompt when I click the start button?

 Game.start.onclick = function Start(){  
  let namePlayer1 = prompt("Hello Player 1 ! What is your name?");
  let namePlayer2 = prompt("Hello Player 2 ! What is your name?"); 

 return alert(namePlayer1 + "- You have the symbol 'X'.\n"+ namePlayer2 +
      "- You have the symbol 'O'.\nClick on the button Change Turn to start!")
 }

Answer 1

What @Jeremy and @Arthur mentioned in the comments could look like this. You should move only declaration of variables outside, not whole initialisation with prompt function call.

let namePlayer1;
let namePlayer2;

Game.start.onclick = function Start() {
    namePlayer1 = prompt("Hello Player 1 ! What is your name?");
    namePlayer2 = prompt("Hello Player 2 ! What is your name?");

    return alert(
      namePlayer1 +
        "- You have the symbol 'X'.\n" +
        namePlayer2 +
        "- You have the symbol 'O'.\nClick on the button Change Turn to start!"
    );
};