Question

function compare(choice1,choice2)
{
    if (choice1 === choice2)
    {
        return "The result is a tie!"
    }
    else if (choice1 === "rock")
    {
        if (choice2 === "scissors")
        return "Rock wins"
    }
    else
    {
        return "Paper wins"
    }
    else if (choice1 === "paper")
    {
        if (choice2 === "rock")
        {
        return "Paper wins"
        }
        else
        {
            return "Scissors wins"
        }
    }
}

错误是第二个if语句。我是编程新手，所以我不知道出了什么问题。该错误表明它期望一个标识符，而不是

Answer 1

if ... else if ... else阻止将以else阻止结束。

那就是你可以用else块来结束它。或者说，在else if

之后else无法到来

这样做：

function compare(choice1,choice2)
{
    if (choice1 === choice2)
    {
        return "The result is a tie!"
    }
    else if (choice1 === "rock")
    {
        if (choice2 === "scissors")
        return "Rock wins"
    }
    else if (choice1 === "paper")
    {
        if (choice2 === "rock")
        {
        return "Paper wins"
        }
        else
        {
            return "Scissors wins"
        }
    }
    else
    {
        return "Paper wins"
    }  
}

Answer 2

如果从 if 块中返回只有一个 else ，那么就不需要其他部分。

function compare(choice1,choice2)
{
    if (choice1 === choice2)
    {
        return "The result is a tie!"
    }

    if (choice1 === "rock")
    {
        if (choice2 === "scissors") 
        {
        return "Rock wins"
        }
        return "Paper wins"
    }

    if (choice1 === "paper")
    {
        if (choice2 === "rock")
        {
        return "Paper wins"
        }
        return "Scissors wins"
    }
}

如果使用条件?:运算符，可以进一步减少：

function compare(choice1,choice2) {
    if (choice1 === choice2) {
        return "The result is a tie!"
    }

    if (choice1 === "rock") {
        return choice2 === "scissors"? "Rock wins" : "Paper wins";
    }

    if (choice1 === "paper") {
        return choice2 === "rock"? "Paper wins" : "Scissors wins";
    }

    // You forgot this one
    if (choice1 === "scissors") {
        return choice2 === "rock"? "Rock wins" : "Scissors wins";
    }
}

当有许多二元选择时，哪个更紧凑，更容易阅读。

期望一个标识符，而是找到其他javascript

2 个答案: