javascript - 用函数改变Javascript变量？

Question

我可以用 var computerChoice = Math.random(); 来做到这一点……并将该变量变成石头、布或剪刀……但现在我无法获得变量“winner” ' 进行更改，以便打印出结果。它只是不断打印出“未定义”。帮助？

 var choice1 = userChoice;
 var choice2 = computerChoice;


 var winner = "undefined";


 var compare = function (choice1, choice2) {//start function

     if (choice1 === choice2) {
         winner = "Tie game!";


     } else if (choice1 === "rock") {
         if (choice2 === "scissors") {
             winner = "rock wins";
         } else {
             winner = "paper wins";
         }
     } else if (choice1 === "paper") {
         if (choice2 === "rock") {
             winner = "paper wins";
         } else {
             winner = "scissors wins";
         }
    } else {
        if (choice2 === "paper") {
            winner = "scissors wins";
        } else {
            winner = "rock wins";
        }
    }

}//end function


confirm("You chose: " + userChoice + "\nSystem: " + computerChoice + "\nOutcome: " + winner);


compare(userChoice,computerChoice);

</script>

Answer 1

那是因为您在显示它之前没有对其进行更改。 在调用confirm之前调用compare，因为compare是改变winner的函数。

compare(userChoice, computerChoice);
confirm("You chose: " + userChoice + "\nSystem: " + computerChoice + "\nOutcome: " + winner);