Question

用户输入输入，单击按钮，并调用函数以执行某些计算。如果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，则该字段需要显示错误消息。如果多个字段错误，则这些字段需要显示错误消息。现在，如果字段错误，页面只显示一条错误消息，即使所有字段都是错误的。我确信这是一个简单的解决办法，但我一直在撞墙。有什么建议？谢谢！以下是代码的适用部分：

    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;
        }

Answer 1

这就是我所做的似乎可以解决问题的方法：

    //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);
        }

Answer 2

如果找到前两个错误之一，您的解决方案仍将进行计算。这是另一种选择：

    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);
    }

JavaScript多个错误消息

2 个答案: