Json array for quiz

Question

大家好我需要一點幫助。我試圖做的是計算答案的數量。 「qu」是問題，「ca」是核心答案。我需要得到陣列

var questions = [{"qu" : "question?","ca0" : "answer1","ca1" : "answer2"}]; 

我想是這樣的答案中的金額，但它不工作。

for(var i = 0; i< 10;i++) 
{ 
    var cax = "ca" + i; 
    if(questions[0].cax == null) 
    { 
     alert("there are " + (i+1) + "answers"); 
     break; 
    } 
} 

任何幫助都會很棒！

Answer 1

根據我對這個問題的理解。您需要使用questions[0][cax]代替questions[0].cax

var questions = [{ 
    "qu": "question?", 
    "ca0": "answer1", 
    "ca1": "answer2" 
}]; 
for (var i = 0; i < 10; i++) { 
    var cax = "ca" + i; 
    if (questions[0][cax] == null) { 
     alert("there are " + (i + 1) + "answers"); 
     break; 
    } 
} 

DEMO

Answer 2

假設我正確地理解你的問題，你想知道有多少元素出現在你的陣列的「問題」：

數量問題中的元素可以通過使用questions.length獲得。

Answer 3

我假設很多東西 - 但是這可能是你在找什麼

for(var i=0; i < questions.length; i++) 
{  
console.log("Number of answers for Question No." + i + " - " + Object.keys(questions[i]).length - 1); 
} 

不會老的瀏覽器上工作 文件here

Answer 4

事情是這樣的，我認爲是你想要的。

var quiz = { 
       questions: [{ 
        question: 'what is 2x2?', 
        answer: 5, 
        correctAnswer: 4 
       }, { 
        question: 'what is 3x2?', 
        answer: 12, 
        correctAnswer: 6 
       }, { 
        question: 'what is 2+4', 
        answer: 6, 
        correctAnswer: 6 
       } 
       ] 
      }; 
      function gradeQuiz(array) { 
       var rightAnswers = 0; 
       for (var i = 0; i < array.questions.length; i++) { 
        if (array.questions[i].answer === array.questions[i].correctAnswer) { 
         rightAnswers++; 
        } 
       } 
       console.log('there were ' + array.questions.length + ' questions'); 
       console.log('you got ' + rightAnswers + ' correct'); 
      } 

      gradeQuiz(quiz); 

Answer 5

這裏是你的答案：

var questions = [{"qu" : "question?","ca0" : "answer1","ca1" : "answer2"}]; 

var nCorrect = 0; 
for (var i=0; i < questions.length; ++i) { 
    var q = questions[i]; 
    for (var p in q) { 
     if (p.indexOf("ca") == 0) 
      nCorrect++; 
    } 
} 

alert("There are " + nCorrect + " answers");