如何在JavaScript中将对象属性添加到数组中？

Question

这是一个小提琴。 http://fiddle.jshell.net/GF9nj/1/我要弄清楚的是为什么当我将对象数据推入randomAnswerArray时，即使在测试<p>中也没有显示。 它大约在JavaScript部分的中间。

这是有问题的代码：

// incorrectAnswer1, incorrectAnswer2, incorrectAnswer3 are initialised elsewhere ...
randomAnswerArray = []; //resets the array to empty
randomAnswerArray.push(randomQuestion.correctAnswer);
document.getElementById('test3').innerHTML=randomAnswerArray[0]; //TESTING doesn't work
randomAnswerArray.push(randomQuestion.incorrectAnswer1);
randomAnswerArray.push(randomQuestion.incorrectanswer2);
randomAnswerArray.push(randomQuestion.incorrectanswer3);
document.getElementById('test1').innerHTML = randomAnswerArray.valueOf();

valueOf（）调用仅显示randomAnswerArray中的0和1项目，但我也同时推2和3。

---

这是小提琴的完整代码：

HTML

var questionList = [];
var randomAnswerArray = [];

// this is the question object constructor

function quizQuestion(question, correctAnswer, incorrectAnswer1, incorrectAnswer2, incorrectAnswer3) {
    this.question = question;
    this.correctAnswer = correctAnswer;
    this.incorrectAnswer1 = incorrectAnswer1;
    this.incorrectAnswer2 = incorrectAnswer2;
    this.incorrectAnswer3 = incorrectAnswer3;
}

// this constructs a question

var hairColor = new quizQuestion("What color is my hair?", "black", "blue", "red", "purple");

// this adds the question to the questionList

questionList.push(hairColor);
document.getElementById('test2').innerHTML = questionList[0].correctAnswer; //TESTING object constructor works
function generate() {

    // this part picks a random question
    var randomQuestion = questionList[Math.floor(Math.random() * questionList.length)];

    // this part puts the question in the questionString
    document.getElementById("questionString").innerHTML = randomQuestion.question;

    // this part puts the answers in the array

    // THIS IS WHAT WE ARE TESTING    VVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVV
    randomAnswerArray = []; //resets the array to empty
    randomAnswerArray.push(randomQuestion.correctAnswer);
    document.getElementById('test3').innerHTML=randomAnswerArray[0]; //TESTING doesn't work
    randomAnswerArray.push(randomQuestion.incorrectAnswer1);
    randomAnswerArray.push(randomQuestion.incorrectanswer2);
    randomAnswerArray.push(randomQuestion.incorrectanswer3);
    document.getElementById('test1').innerHTML = randomAnswerArray.valueOf(); //TESTING doesn't work
    // ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^    
    // this part randomizes the array

    var currentIndex = randomAnswerArray.length;
    var temporaryValue;
    var randomIndex;
    while (0 !== currentIndex) {
        randomIndex = Math.floor(Math.random() * currentIndex);
        currentIndex -= 1;
        temporaryValue = randomAnswerArray[currentIndex];
        randomAnswerArray[currentIndex] = randomAnswerArray[randomIndex];
        randomAnswerArray[randomIndex] = temporaryValue;
    }
}

JavaScript的

 var questionList = []; var randomAnswerArray = []; // this is the question object constructor function quizQuestion(question, correctAnswer, incorrectAnswer1, incorrectAnswer2, incorrectAnswer3) { this.question = question; this.correctAnswer = correctAnswer; this.incorrectAnswer1 = incorrectAnswer1; this.incorrectAnswer2 = incorrectAnswer2; this.incorrectAnswer3 = incorrectAnswer3; } // this constructs a question var hairColor = new quizQuestion("What color is my hair?", "black", "blue", "red", "purple"); // this adds the question to the questionList questionList.push(hairColor); document.getElementById('test2').innerHTML = questionList[0].correctAnswer; //TESTING object constructor works function generate() { // this part picks a random question var randomQuestion = questionList[Math.floor(Math.random() * questionList.length)]; // this part puts the question in the questionString document.getElementById("questionString").innerHTML = randomQuestion.question; // this part puts the answers in the array // THIS IS WHAT WE ARE TESTING VVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVV randomAnswerArray = []; //resets the array to empty randomAnswerArray.push(randomQuestion.correctAnswer); document.getElementById('test3').innerHTML=randomAnswerArray[0]; //TESTING doesn't work randomAnswerArray.push(randomQuestion.incorrectAnswer1); randomAnswerArray.push(randomQuestion.incorrectanswer2); randomAnswerArray.push(randomQuestion.incorrectanswer3); document.getElementById('test1').innerHTML = randomAnswerArray.valueOf(); //TESTING doesn't work // ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ // this part randomizes the array var currentIndex = randomAnswerArray.length; var temporaryValue; var randomIndex; while (0 !== currentIndex) { randomIndex = Math.floor(Math.random() * currentIndex); currentIndex -= 1; temporaryValue = randomAnswerArray[currentIndex]; randomAnswerArray[currentIndex] = randomAnswerArray[randomIndex]; randomAnswerArray[randomIndex] = temporaryValue; } } 

Answer 1

嗯，函数生成不存在，因为JsFiddle在onLoad事件中将javascript代码添加为函数。 这使得generate函数可以在其他私有上下文中声明。 我建议添加js代码

window.generate = generate;

作为代码的最后一个。 这样，您将在全局名称空间中设置generate函数。 并且您的onClick事件将正确调用它。 如果解决此问题，脚本将正常运行。

我也为您更新了小提琴： http : //fiddle.jshell.net/GF9nj/9/

Answer 2

这就是问题所在。 这是JSFiddle的事情。 在Framework and Extensions选项下设置no wrap in body。 javascript的加载方式，您的函数在您所认为的范围内不可见。 如果您愿意，我可以在编辑中进一步解释

默认情况下，JSFiddle将JS包装在文档的onload事件中。 因此，您的功能不是在您想像的根范围内定义的，而是在document.onload函数的范围内定义的，您无法从主体内部访问它，因为那是在该函数之外。 我将JsFiddle属性'wrap in'更改为'no wrap（body）'并且它起作用了。

您确实不应该将函数与onclick标记绑定。 更好的解决方案是从按钮中删除onclick，然后将其替换为id="button"

然后在您的JavaScript的底部， document.getElementById('start').onclick=generate

Answer 3

在您的推送语句中，您拼错了这些

 incorrectAnswer2
 incorrectAnswer3

如

incorrectanswer2
incorrectanswer3