var user, password;
user = prompt("Who's there?");
switch (user) {
    case "admin":
        password = prompt("Password?");
        (password === "TheMaster")
            ? alert("welcome")
            : (password == null) 
                ? console.log("canceled")
                : alert("Wrong password!");
        break;
    case null:
        console.log("canceled")
        break;
    default:
        alert("i dont know you")
        break;
}