我的石头剪刀布脚本不起作用。控制台日志：未捕获的 SyntaxError：已声明标识符“playerSelection”

Question

I just started learning javaScript and my first proyect is to make a Rock Paper Scissors game that plays on the console, the code that I wrote is:我刚开始学习javaScript，我的第一个项目是制作一个在控制台上玩的石头剪刀布游戏，我写的代码是：

<!DOCTYPE html>
<html>
<body>
<script>

    let RPS = function playRound (playerSelection, computerSelection) {

    let playerSelection = promt ("What do you choose?", "");

    let computerSelection = math.Random ();
        if computerSelection (<0.34) {
            computerSelection = "Rock";
        } else if computerSelection (>=0.35 && <=0.66) {
                computerSelection = "Paper";
        } else {
                computerSelection = "Scissors";
        }

    if (playerSelection === "Rock"){
        if (computerSelection === "Scissors") {
            console.log ("You win");
        } else {
            console.log ("You lose");
        }
    }    
    if (playerSelection === "Paper") {
        if (computerSelection === "Scissors"){
            console.log ("You win");
        }else {
            console.log ("You lose")
        }    
    }
    if (playerSelection === "Scissors") {
        if (computerSelection ==== "Paper"){
            console.log ("You win")
        } else {
            console.log ("You lose")
        }
    }

    }

</script>
</body>
</html>

When I try to run this on the console I get当我尝试在控制台上运行它时，我得到

Uncaught SyntaxError: Identifier 'playerSelection' has already been declared

Why is that?这是为什么？

Answer 1

The error is very straight forward.错误非常直接。 You are passing arguments named playerSelection and computerSelection then you immediately try to declare two local variables of the same name - however, arguments are considered local variables themselves, so you are indeed duplicating.您正在传递名为playerSelection和computerSelection参数，然后您立即尝试声明两个同名的局部变量 - 但是，参数本身被视为局部变量，因此您确实在重复。 Either pass the variables to the function as arguments or declare them in the code using let , not both.要么将变量作为参数传递给函数，要么使用let在代码中声明它们，而不是两者都使用。

Additionally, your code is riddled with syntax errors, you definitely need to proof-read this code because it will not run even if you fix the issue you ask about in the question.此外，您的代码充满了语法错误，您绝对需要校对此代码，因为即使您解决了您在问题中提出的问题，它也不会运行。

Here is an example of what you probably want:以下是您可能想要的示例：

 let RPS = function playRound() { let playerSelection = prompt("What do you choose?", ""); let computerSelection = Math.random(); if (computerSelection < 0.34) { computerSelection = "Rock"; } else if (computerSelection >= 0.35 && computerSelection <= 0.66) { computerSelection = "Paper"; } else { computerSelection = "Scissors"; } if (playerSelection === "Rock") { if (computerSelection === "Scissors") { console.log("You win"); } else { console.log("You lose"); } } if (playerSelection === "Paper") { if (computerSelection === "Scissors") { console.log("You win"); } else { console.log("You lose") } } if (playerSelection === "Scissors") { if (computerSelection === "Paper") { console.log("You win") } else { console.log("You lose") } } } RPS()

我的石头剪刀布脚本不起作用。控制台日志：未捕获的 SyntaxError：已声明标识符“playerSelection”

问题描述

1 个解决方案

解决方案1
1 已采纳 2020-01-09 18:07:14

我的石头剪刀布脚本不起作用。 控制台日志：未捕获的 SyntaxError：已声明标识符“playerSelection”

问题描述

1 个解决方案

解决方案1 1 已采纳 2020-01-09 18:07:14

我的石头剪刀布脚本不起作用。控制台日志：未捕获的 SyntaxError：已声明标识符“playerSelection”

解决方案1
1 已采纳 2020-01-09 18:07:14