Question

不确定我的代码是否正常运行，但是我看到的错误是“已声明“结果”，但其值从未读取。ts（6133）”

这只是一个介绍性练习，因此我对如何完成同一件事持开放式建议/指导。我这样做的方式是针对事件类型使用三个IF语句，并在每个温度范围内嵌套IF语句。

let eventType = window.prompt("What type of event are you going to?");
let tempFahr = window.prompt("What is will the temperature be?");


if (eventType=='casual') { // casual event

    if (tempFahr < 54) { // temp less than 54
        let result = 'Since it is ' + tempFahr + ' and you are going to a ' + eventType + ' event, you should wear something comfy and a coat';
    } else if (54 < tempFahr < 70) { // temp between 54 and 70
        let result = 'Since it is ' + tempFahr + ' and you are going to a ' + eventType + ' event, you should wear something comfy and a jacket';
    } else { // temp more than 70
        let result = 'Since it is ' + tempFahr + ' and you are going to a ' + eventType + ' event, you should wear something comfy and no jacket';
    }
} else if (eventType=='semi-formal') { // semi-formal event
    if (tempFahr .. (Etc.)...


``````````````

    {
        let result = 'Since it is ' + tempFahr + ' and you are going to a ' + eventType + ' event, you should wear a suit and no jacket';
    }
}

    console.log(result);

Answer 1

let是块作用域的-您需要在result语句之外声明if：

let eventType = window.prompt("What type of event are you going to?");
let tempFahr = window.prompt("What is will the temperature be?");
let result = "";
if (eventType == "casual"){
    if (tempFahr < 54){
        result = 'Since it is ' + tempFahr + ' and you are going to a ' + eventType + ' event, you should wear something comfy and a coat';
    }
    //...
}
else if (eventType == "semi-formal") {...}
console.log(result);

块作用域确定意味着用let或const在代码{}的“块”中声明不会在该块外部存在，而仅在其内部。因此，let result = "..."语句内的if意味着result将被删除，而其他所有将完全不同。它们将被垃圾回收，因为在if语句之外没有对它们的引用。

变量在嵌套IF内部声明但在外部读取？这有问题吗？

1 个答案: