Question

我正在处理这个添加问题工作表，我让它在Chrome中运行并运行，但下一个问题按钮无法正常工作。这是我的第一个Javascript程序。我通过验证器运行它并将其归结为1错误，但是注释掉该行似乎没有帮助。

以下是整个Javascript部分：

 <script type="text/javascript">

var questionTop = new Array(); //Array to store the top random number of questions
var questionBot = new Array(); //Array to store the bottom random number of questions
var answers = new Array(); //Array to store the answers the user enters
var correct = new Array(); //Array to store the correct answers
var questionMarker = 0; //Loop counter for number of times through
var correctAnswers = 0; //Counter for number of correct answers

function startQuiz() {
    questionMarker = 0;  //Function starts the quiz and resets the form
    correctAnswers = 0;  //so that the first random numbers show up and hides the start button
    document.getElementById('startButton').style.visibility='hidden';
    document.getElementById('nextQuestion').style.visibility='visible';
    document.getElementById('firstAdd').innerHTML=randomNumber();
    document.getElementById('secondAdd').innerHTML=randomNumber();
}

function randomNumber()
{
    var number = Math.floor(Math.random()*50) + 1; //Generates a random number between 1-50
    return number;
}

function nextQuestion()
{
    if(txtAnswer.value === "") //Check to see if they answered the question
    {
        alert("You didn't answer the question."); //Tell them they didn't
    }
    else
    {
        questionTop[questionMarker] = document.getElementById('firstAdd').innerHTML * 1; //Stores the top random number in the array
        questionBot[questionMarker] = document.getElementById('secondAdd').innerHTML * 1; //Stores the bottom random number in the array
        answers[questionMarker] = txtAnswer.value; //Stores the answer given by the user
        correct[questionMarker] = questionTop[questionMarker] + questionBot[questionMarker]; //Calculates and stores the correct answer
        if(answers[questionMarker] == correct[questionMarker]) //Checks to see if they got the answer right
        {
            alert("You got the question right!"); //Tells them so
            correctAnswers++; //Counts the correct answer for later
        }
        else
        {
            alert("Sorry that was not the correct answer." + '\n' + "You answered " + answers[questionMarker] + '\n' + "The correct answer was " + correct[questionMarker]); //Tells them the answer if they got it wrong and compares to their answer
        }
        document.getElementById('firstAdd').innerHTML=randomNumber(); //Generates new top random number
        document.getElementById('secondAdd').innerHTML=randomNumber(); //Generates new bottom random number
        txtAnswer.value = ""; //Clears the answer field
        txtCarry.value = ""; //Clears the carry field
        questionMarker++; //Increments the questionMarker so we know how many questions we've answered.
    }
    if(questionMarker == 10) //If we've answered 10 questions...
    {
        alert("You have completed the quiz!"); //The quiz is completed
        document.write("Your Answers:"); //Displays their answers
        document.write('\n' + questionTop[0] + " + " + questionBot[0] + " = " + answers[0] + "  Correct Answer is: " + correct[0]);
        document.write('\n' + questionTop[1] + " + " + questionBot[1] + " = " + answers[1] + "  Correct Answer is: " + correct[1]);
        document.write('\n' + questionTop[2] + " + " + questionBot[2] + " = " + answers[2] + "  Correct Answer is: " + correct[2]);
        document.write('\n' + questionTop[3] + " + " + questionBot[3] + " = " + answers[3] + "  Correct Answer is: " + correct[3]);
        document.write('\n' + questionTop[4] + " + " + questionBot[4] + " = " + answers[4] + "  Correct Answer is: " + correct[4]);
        document.write('\n' + questionTop[5] + " + " + questionBot[5] + " = " + answers[5] + "  Correct Answer is: " + correct[5]);
        document.write('\n' + questionTop[6] + " + " + questionBot[6] + " = " + answers[6] + "  Correct Answer is: " + correct[6]);
        document.write('\n' + questionTop[7] + " + " + questionBot[7] + " = " + answers[7] + "  Correct Answer is: " + correct[7]);
        document.write('\n' + questionTop[8] + " + " + questionBot[8] + " = " + answers[8] + "  Correct Answer is: " + correct[8]);
        document.write('\n' + questionTop[9] + " + " + questionBot[9] + " = " + answers[9] + "  Correct Answer is: " + correct[9]);
        document.write('\n' + "You got " + correctAnswers + " answers right out of 10."); //Shows how many answers they got right
        document.write('\n' + "You got " + correctAnswers*10 + "% of the questions right."); //Calculates their percent right
        document.write('\n' + '<button id="newQuiz" type="button" onclick="window.location.reload()">New Quiz</button>'); //Creates new button to reload the screen and start again
    }
}

</script>

它位于网络上： http://www.innogeek.com/java/index.html 代码位于http://www.innogeek.com/java/frame.html

的iFrame中

Answer 1

将nextQuestion()更改为：

function nextQuestion()
{
    var txtAnswer = document.getElementById('txtAnswer'); //<-- ADD THIS
    var txtCarry = document.getElementById('txtCarry'); //<-- AND THIS

    if(txtAnswer.value === "") //Check to see if they answered the question
    {
        alert("You didn't answer the question."); //Tell them they didn't
    }
...
}

您的问题是在使用它之前没有定义txtAnswer变量。

有些浏览器会自动将DOM ID映射到Javascript变量（我相信IE也会这样做），但是你无法真正依赖它。

Answer 2

在使用之前，您尚未声明txtAnswer变量。

Answer 3

您的问题是没有名为txtAnswer的已定义变量。我认为Chrome将带有id的DOM元素映射到具有相同名称的变量（这是您不能依赖的行为）。我建议您添加此行以开始nextQuestion功能：

var txtAnswer = document.getElementById("txtAnswer");

适用于Chrome的Javascript，但没有其他功能

3 个答案: