我是在JavaScript中正确嵌套这些if / else if语句吗？

Question

我正在使用JavaScript制作摇滚，纸张，剪刀游戏，我必须让用户知道是否有领带，如果除了摇滚，纸张和剪刀之外还有无效的用户选择，那么我认为如果嵌套， / else语句是合适的。我是JS的新手，无法判断我的代码无法正常工作的原因是嵌套不正确还是其他问题。我得到的只是一个意外令牌的解析错误。

var UserChoice = window.prompt("Select rock, paper, or scissors");

var computChoice = Math.random();
if (computChoice <= 0.33) {
    computChoice = "scissors";
} else if (computChoice <= 0.66 && computChoice > 0.33) {
    computChoice = "paper";
} else {
    computChoice = "rock";
}

if (UserChoice === "paper") {
    if (UserChoice === "paper" && computChoice === "rock") {
        window.alert("You chose paper and the computer chose rock! You win! Paper covers rock");  
    } else if (UserChoice === "paper" && computChoice === "paper") {
        window.alert("It's a tie!");
    } else if (UserChoice === "paper" && computChoice === "scissors") {
        window.alert("You lose! You chose paper and computer chose scissors. Scissors cut paper!");
    } 
} else if (UserChoice === "scissors") {
    if (UserChoice === "scissors" && computChoice === "paper") {
        window.alert("You chose scissors and the computer chose paper! You win! Scissors cut paper.");
    } else if (UserChoice === "scissors" && computChoice === "scissors") {
        window.alert("It's a tie! You chose scissors and the computer chose scissors!");
    } else if (UserChoice === "scissors" && computChoice === "rock") {
        window.alert("You lose! You chose scissors and computer chose rock. Rock smashes scissors!");
    }
} else if (UserChoice === "rock") {
    if (UserChoice === "rock" && computChoice === "scissors") {
        window.alert("You chose rock and the computer chose scissors! You win! Rock smashes scissors."); 
    } else if (UserChoice === "rock" && computChoice === "rock") {
        window.alert("It's a tie! You chose rock and the computer chose rock!");
    } else if (UserChoice === "scissors" && computChoice === "rock") {
        window.alert("You lose! You chose rock and computer chose paper. Paper covers rock!");
} else {
    window.prompt("Invalid choice! Choose from rock, paper, or scissors");
}

Answer 1

您的问题不是您的代码的问题。这是一个简单的语法错误。

你在最后错过了一个}来关闭外部的if语句。我更新了您的代码段以使其在下方运行。

var UserChoice = window.prompt("Select rock, paper, or scissors");

var computChoice = Math.random();
if (computChoice <= 0.33) {
  computChoice = "scissors";
} else if (computChoice <= 0.66 && computChoice > 0.33) {
  computChoice = "paper";
} else {
  computChoice = "rock";
}

if (UserChoice === "paper") {
  if (UserChoice === "paper" && computChoice === "rock") {
    window.alert("You chose paper and the computer chose rock! You win! Paper covers rock");
  } else if (UserChoice === "paper" && computChoice === "paper") {
    window.alert("It's a tie!");
  } else if (UserChoice === "paper" && computChoice === "scissors") {
    window.alert("You lose! You chose paper and computer chose scissors. Scissors cut paper!");
  }
} else if (UserChoice === "scissors") {
  if (UserChoice === "scissors" && computChoice === "paper") {
    window.alert("You chose scissors and the computer chose paper! You win! Scissors cut paper.");
  } else if (UserChoice === "scissors" && computChoice === "scissors") {
    window.alert("It's a tie! You chose scissors and the computer chose scissors!");
  } else if (UserChoice === "scissors" && computChoice === "rock") {
    window.alert("You lose! You chose scissors and computer chose rock. Rock smashes scissors!");
  }
} else if (UserChoice === "rock") {
  if (UserChoice === "rock" && computChoice === "scissors") {
    window.alert("You chose rock and the computer chose scissors! You win! Rock smashes scissors.");
  } else if (UserChoice === "rock" && computChoice === "rock") {
    window.alert("It's a tie! You chose rock and the computer chose rock!");
  } else if (UserChoice === "scissors" && computChoice === "rock") {
    window.alert("You lose! You chose rock and computer chose paper. Paper covers rock!");
  } else {
    window.prompt("Invalid choice! Choose from rock, paper, or scissors");
  }
}

Answer 2

在您的情况下，您只需将}添加到代码的末尾。

但是还有其他方法来创建rock, paper, scissors game：

var UserChoice = window.prompt("Select rock, paper, or scissors");

var computChoice = Math.random();

var computChoice = computChoice < 0.33 ? "scissors" : ( computChoice > 0.66 ? "rock" : "paper" ) ;

var mess = { 
  rock : { scissors : 'You Win!, Rock smashes scissors!', paper : 'You lose!, Paper covers rock!'} ,
  paper : { rock : 'You Win!, Paper covers rock!', scissors : 'You lose!, Scissors cut paper!' },
  scissors : { paper : 'You Win!, Scissors cut paper!', rock : 'You lose!, Rock smashes scissors!' }
}

if ( computChoice === UserChoice)
  result = "It's a tie!" ; 
	 
else if ( UserChoice !== "rock" && UserChoice !== "paper" && UserChoice !== "scissors" )
  result = "Invalid choice! Choose from rock, paper, or scissors" ;

else
  result = mess[UserChoice][computChoice] ;

console.log( 'you chose ' + UserChoice + ' and computer chose ' + computChoice + ' ( ' + result + ' ) ') ;