javascript - 无法获取未定义的属性 "userResponse"

Question

我尝试通过构建 travia 游戏应用程序来学习 NativeScript。 我有一个如下所示的问题 json 列表:

var questionsList20 = {"questions" : [{"question":"Taxing a commodity at the production level decreases supply.","correctAnswer":"answerOne","answerOne":"True","answerTwo":"False","answerThree":"Uncertain","answerFour":"None of the above","userResponse":"","explanationTwo":"True","grade":""},{"question":"The circular flow depicts the alternative combination of goods and services an economy \tcan produce at a point in time.","correctAnswer":"answerTwo","answerOne":"True","answerTwo":"False","answerThree":"Uncertain","answerFour":"None of the above","userResponse":"","explanationTwo":"False","grade":""},{"question":"Demand is inelastic if elasticity of demand < 0.","correctAnswer":"answerTwo","answerOne":"True","answerTwo":"False","answerThree":"Uncertain","answerFour":"None of the above","userResponse":"","explanationTwo":"False","grade":""},{"question":"Elasticity of demand measures the percentage change in the quantity demand of a commodity as a result of a given percentage change in price.","correctAnswer":"answerTwo","answerOne":"True","answerTwo":"False","answerThree":"Uncertain","answerFour":"None of the above","userResponse":"","explanationTwo":"False","grade":""}]}

为了获得个人问题，我正在这样做:

questionViewModel.startNewGame = function () {


    for (var i = 0; i < questionViewModel.numberOfQuestions - 1; i++) {
        questionViewModel.test.questions[i].userResponse = "";
        questionViewModel.test.questions[i].grade = "";
    }
}

起初它有效，但后来我收到无法设置未定义的属性 userResponse 的错误。

我不知道如何解决这个问题。请帮忙。

Answer 1

您可以尝试初始化一个空的问题数组，并将每个问题像问题对象一样推送。

questionViewModel.startNewGame = function () {
    questionViewModel.test.questions = [];

    for (var i = 0; i < questionViewModel.numberOfQuestions; i++) {
        questionViewModel.test.questions.push({"userResponse": "", "grade": ""});
    }
}