我已经盯着我的代码几个小时了，找不到它出了什么问题。 -Javascript

Question

问题出在displayInfo函数中。 我运行了程序，一切正常，但没有输出。 输出应该全部放在一个框中，并且应该看起来像我将提供的图片，但是要用上所有的几个月。 输出示例

function main() {
    alert("Welcome to the program");

    var endProgram = "no";

    while (endProgram == "no") {
        var notGreenCosts = [12];
        var goneGreenCosts = [12];
        var savings = [12];
        var months = ["January", "February", "March  ", "April  ", "May   ", "June   ", "July   ", "August", "September", "October", "November", "December"];

        getNotGreen(notGreenCosts, months);
        getGoneGreen(goneGreenCosts, months);
        energySaved(notGreenCosts, goneGreenCosts, savings);
        displayInfo(notGreenCosts, goneGreenCosts, savings, months);

        endProgram = prompt("Do you want to end the program? Yes or no?");
    }
}


function getNotGreen(notGreenCosts, months) {
    var counter = 0;
    while (counter < 12) {
        notGreenCosts[counter] = parseFloat(prompt("Enter NOT GREEN energy costs for " + months[counter]));
        counter++;
    }
}


function getGoneGreen(goneGreenCosts, months) {
    var counter = 0;
    while (counter < 12) {
        goneGreenCosts[counter] = parseFloat(prompt("Enter GONE GREEN energy costs for " + months[counter]));
        counter++;
    }
}

function energySaved(notGreenCosts, goneGreenCosts, savings) {
    var counter = 0;
    while (counter < 12) {
        savings[counter] = parseFloat((notGreenCosts[counter] - goneGreenCosts[counter]));
        counter++;
    }
}

function displayInfo(notGreenCosts, goneGreenCosts, savings, months) {
    var counter = 0;
    var outputString = "Month \t\t\t not green \t gone green \t savings \n\n";

    while (counter < 12) {
        outputString += months[counter] + "\t\t\t" + notGreenCosts[counter] + "\t\t\t" + goneGreenCosts[counter] + "\t\t\t" + savings[counter] +  "\r\n";

        counter++;
    }

}

main();
alert("End of program");

Answer 1

实际上，您没有在displayInfo方法中显示任何内容：

function displayInfo(notGreenCosts, goneGreenCosts, savings, months) {
    var counter = 0;
    var outputString = "Month \t\t\t not green \t gone green \t savings \n\n";

    while (counter < 12) {
        outputString += months[counter] + "\t\t\t" + notGreenCosts[counter] + "\t\t\t" + goneGreenCosts[counter] + "\t\t\t" + savings[counter] +  "\r\n";

        counter++;
    }
  alert(outputString); // -----> add this line
}

另一个问题

还有另一个问题不会引起任何问题，但是您似乎误解了数组声明。
您的var notGreenCosts = [12]; 应该更改为var notGreenCosts = new Array(12); 。 与其他数组声明相同。
检查： https ： //developer.mozilla.org/zh-CN/docs/Web/JavaScript/Reference/Global_Objects/Array

Answer 2

我重新编写了您的代码，并提出了这个建议。 我添加了评论，可帮助您了解发生了什么。 我将在您的原始代码中添加摘要，并在后面添加注释。

编辑和评论

您只有一个要循环的数组，因此只需要一个while循环。

您要在此处初始化所有具有相同数字值的数组。 不需要。

var notGreenCosts = [12];
var goneGreenCosts = [12];
var savings = [12]; 

在函数中，您尝试使用循环中传递的计数器从数组中获取值。 如果使用嵌套的while循环来执行该功能。

function getNotGreen(notGreenCosts, months) {
            var counter = 0;
            while (counter < 12) {
                notGreenCosts[counter] = parseFloat(prompt("Enter NOT GREEN energy costs for " + months[counter]));
                counter++;
            }
        }

然后您将获得：

notGreenCosts[0] // returns 12             months[0] // returns January 
notGreenCosts[1] // returns undefined      months[1] // returns February 
notGreenCosts[2] // returns undefined      months[2] // returns March 
notGreenCosts[3] // returns undefined      months[3] // returns April 
notGreenCosts[4] // returns undefined      months[4] // returns May 

可以通过初始化它们来设置这些变量，并将其传递给函数的顶部。 没有将它们设置为数组。

var notGreenCosts = [12];

但是我继续进行初始化，并将它们分配给一行中的返回函数值。

var notGreenCosts = getNotGreen(months, counter);

工作守则

函数main（）{alert（“欢迎使用该程序”）;

        //inital "End Program" answer
        var endProgram = "no";
        // Array of Months
        var months = ["January", "February", "March  ", "April  ", "May   ", "June   ", "July   ", "August", "September", "October", "November", "December"];
        var counter = 0;
        //inital coounter value. Set to ero to match the zero index months array

        // while loop will iterate over the months on at a time until it reaches the end of the array. index 11.
        while (counter < 11) {

            //if the answer to the ed progrm promt question is "no" then run the function and fet the answers.
            if (endProgram === "no") {
                var notGreenCosts = getNotGreen(months, counter); // run the getNotGreen function and assign the returned value to the notGreenCosts variable.
                var goneGreenCosts = getGoneGreen(months, counter); // run the getGoneGreen function and assign the returned value to the goneGreenCosts variable.
                var savings = energySaved(notGreenCosts, goneGreenCosts); // run the energySaved function and assign the returned value to the savings variable.
                var outPit = displayInfo(notGreenCosts, goneGreenCosts, savings, months, counter); // run the displayInfo function and assign the returned value to the outPit variable.

                console.log(outPit); // pint the out come to the console. 

                // end the program alert.
                endProgram = prompt("Do you want to end the program? Yes or no?");
            } else {
                return // user wants to end the program. Jumps to the end alert.
            }
            counter++; //add 1 to the counter.
        }
    }

    function getNotGreen(months, counter) {
        var answer = parseFloat(prompt("Enter NOT GREEN energy costs for " + months[counter])); // insure that the intered number is a whole number
        return answer; // return the anwser.
    }

    function getGoneGreen(goneGreenCosts, months, counter) {
        var answer = parseFloat(prompt("Enter GONE GREEN energy costs for " + months[counter])); // insure that the intered number is a whole number
        return answer; // return the anwser.
    }

    function energySaved(notGreenCosts, goneGreenCosts) {
        return parseFloat((notGreenCosts - goneGreenCosts)); // return the calulated number and insure that is a whole number.
    }

    function displayInfo(notGreenCosts, goneGreenCosts, savings, months, counter) {
        var outputString = "Month \t\t\t not green \t gone green \t savings \n\n";
        return outputString += months[counter] + "\t\t\t\t" + notGreenCosts + "\t\t\t" + goneGreenCosts + "\t\t\t\t" + savings + "\r\n"; // return the value string. 
    }

    //run the program.
    main();
    // end the program
    alert("End of program");