在try-catch-finally中使用else-if语句

Question

我想使用try-catch-finally语句错误检查用户输入，然后在没有错误的情况下进入下一页（我知道有更简单的方法来做到这一点，但我被要求使用try-catch-finally）。在这种情况下：foo是用户的输入，输入需要是介于0和100之间的数字，而displayDiagram（）会将用户推到下一页。

一切都适合我，直到finally块。如果用户根本没有输入任何内容，则前进到下一张幻灯片。如果没有输入任何内容，我该如何阻止它前进？

下面的代码：

try { 
     if (foo == "") throw "Enter your estimated score"; 
     if (isNaN(foo)) throw "Only use numbers for your estimated score"; 
     if (foo < 0) throw "Estimated score is not valid. Enter a higher number"; 
     if (foo > 100) throw "Estimated score is too high. Enter a lower number"; 

    } 
    catch(err) { 
    document.getElementById("fooMessage").innerHTML = err; 
    document.getElementById("fooInput").style.borderColor = "red"; 

    } 
    finally { 
    if (err = undefined) { 
    displayDiagram(); 
    } 
} 

另一个finally块我曾尝试包括：

finally { 
     if (preScore >= 0 && preScore <= 100) { 
     displayDiagram(); 
     } else if (typeof preScore != "string") { 
     displayDiagram(); 
     } 
     } 

任何想法？谢谢！

Answer 1

你根本就不

try { 
     if (foo == "") throw "Enter your estimated score"; 
     if (isNaN(foo)) throw "Only use numbers for your estimated score"; 
     if (foo < 0) throw "Estimated score is not valid. Enter a higher number"; 
     if (foo > 100) throw "Estimated score is too high. Enter a lower number"; 
     // any throw above will mean this doesn't get executed 
     displayDiagram(); 

    } 
    catch(err) { 
    document.getElementById("fooMessage").innerHTML = err; 
    document.getElementById("fooInput").style.borderColor = "red"; 

    }