JavaScript多个错误消息

用户输入输入，单击一个按钮，然后调用一个函数来执行一些计算。如果某个字段的类型或值不正确，则会显示错误消息。如果其中一个字段错误，那么该字段需要显示错误消息。如果多个字段错误，那么这些字段需要显示错误消息。现在，即使所有字段都是错误的，如果字段错误，页面也只显示一条错误消息。我确信这是一个简单的解决方法，但我一直在撞墙。有什么建议么？谢谢！这里是代码适用部分：JavaScript多个错误消息

if (isNaN(theMilesDriven) || theMilesDriven <= 0) { 
      theMilesDrivenError.firstChild.nodeValue = "Please enter a number greater than 0 for the miles driven."; 
      return false; 
     } 

     if (isNaN(theGallonsUsed) || theGallonsUsed <= 0) { 
      theGallonsUsedError.firstChild.nodeValue = "Please enter a number greater than 0 for the gallons of gas used."; 
      return false; 
     } 

     if (isNaN(thePriceGallon) || thePriceGallon <= 0) { 
      thePriceGallonError.firstChild.nodeValue = "Please enter a number greater than 0 for the price per gallon."; 
      return false; 
     }

来源

2016-03-05 MatthewSpire

'return'语句立即退出函数。 – Pointy

删除'return'语句 –

因此，如果我完全删除了返回语句并将计算放在else语句中，那么这看起来像是一个有效的修复吗？谢谢！ – MatthewSpire

您的解决方案仍然会计算如果前两个错误之一被发现。这里有一个替代方案：

var isErrorFound = false; 

    if (isNaN(theMilesDriven) || theMilesDriven <= 0) { 
     theMilesDrivenError.firstChild.nodeValue = "Please enter a number greater than 0 for the miles driven."; 
     isErrorFound = true; 
    } 

    if (isNaN(theGallonsUsed) || theGallonsUsed <= 0) { 
     theGallonsUsedError.firstChild.nodeValue = "Please enter a number greater than 0 for the gallons of gas used."; 
     isErrorFound = true; 
    } 

    if (isNaN(thePriceGallon) || thePriceGallon <= 0) { 
     thePriceGallonError.firstChild.nodeValue = "Please enter a number greater than 0 for the price per gallon."; 
     isErrorFound = true; 
    } 

    if (!isErrorFound) { 
     //Perform the calculations and write the results to the page 
     var milesPerGallon = theMilesDriven/theGallonsUsed; 
     var theMPG = document.getElementById("mpg"); 
     theMPG.firstChild.nodeValue = "Your MPG is: " + milesPerGallon.toFixed(2); 

     var cost = theGallonsUsed * thePriceGallon; 
     var theCost = document.getElementById("cost"); 
     theCost.firstChild.nodeValue = "Your cost for this trip is: $" + cost.toFixed(2); 
    }

来源

2016-03-05 18:38:09 ConnorsFan

谢谢！我想我现在已经明白了。我提出了您的建议更改以及其他一些更改。我感谢您的帮助。 – MatthewSpire

不客气！ – ConnorsFan

这里就是我所做的，似乎要解决的问题：

//Verify the input is numerical and greater than 0 
     if (isNaN(theMilesDriven) || theMilesDriven <= 0) { 
      theMilesDrivenError.firstChild.nodeValue = "Please enter a number greater than 0 for the miles driven."; 
     } 

     if (isNaN(theGallonsUsed) || theGallonsUsed <= 0) { 
      theGallonsUsedError.firstChild.nodeValue = "Please enter a number greater than 0 for the gallons of gas used."; 
     } 

     if (isNaN(thePriceGallon) || thePriceGallon <= 0) { 
      thePriceGallonError.firstChild.nodeValue = "Please enter a number greater than 0 for the price per gallon."; 
     } 

     else { 
      //Perform the calculations and write the results to the page 
      var milesPerGallon = theMilesDriven/theGallonsUsed; 
      var theMPG = document.getElementById("mpg"); 
      theMPG.firstChild.nodeValue = "Your MPG is: " + milesPerGallon.toFixed(2); 

      var cost = theGallonsUsed * thePriceGallon; 
      var theCost = document.getElementById("cost"); 
      theCost.firstChild.nodeValue = "Your cost for this trip is: $" + cost.toFixed(2); 
     }

来源

2016-03-05 18:34:35 MatthewSpire

这要归功于其他人的建议，我们非常感谢。 – MatthewSpire

JavaScript多个错误消息

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