如何保持选择上一个答案?(javascript测试）

1. 添加答案array以存储答案

   var answers = [];

2. 当点击按钮时更新答案的值，让正确的答案最终被计算出来。

   函数checkAnswer（）｛

   choice = document.getElementsByName("answerswerChoice");
   var checkedAnswer = null;
   for (var i = 0; i < choice.length; i++) {
       if(choice[i].checked) {
           answers[pos] = choice[i].value;
       }
   }
   if( answers[pos] == null ) {
       document.getElementById("error").innerHTML = 'Please select an answer'
       return false;
   }
   pos++
   renderQuestions()
   

   }

3. 渲染完成后更改输入，将检查设置为无线电

   if (typeof answers[pos] !== undefined) {
       var radios = document.getElementsByName('answerChoice');
       var rLen = radios.length, i;
       for (i = 0; i < rLen; ++i) {
           if (answers[pos] === radios[i].value) {
           radios[i].checked = true;
           }
       }
   }
   

4. 输出的计算结果

   if(pos >= allQuestions.length) {
   // Check answers
   var qLen = allQuestions.length, correct = 0;
   for (var i = 0; i < qLen; ++i) {
       if (answers[i] === allQuestions[i].answer) {
           ++correct;
       }
   }
   testStatus.innerHTML = "Test Completed";
   test.innerHTML = "<h2>" + "You got " + correct  + " out of " +  allQuestions.length + "</h2><br/>";
   pos = 0;
   return false
   };
   

使用已工作的jsFiddle

实际上，我只是将答案保存在您的对象allQuestions中。

即在检查中答案：

allQuestions[pos].userAnswer = checkedAnswer;

当你在renderQuestion（）中编写HTML时：

test.innerHTML += 
    '<input type="radio" value="A" name="answerswerChoice" '
    + (allQuestions[pos].userAnwer == 1 ? 'checked' : '')
    + ' /> ' + A + '<br />';

这对于检查基于字符串的答案并不理想，但这应该是一个良好的开端。

编辑：我更新了fiddle：https://jsfiddle.net/4bnx8acw/13/

我通过将位置号保存到数组中并在之后检查它是否相同来修复它

function renderQuestions() {
var testStatus = getID("test_status");
var test = getID("test");
if (pos >= allQuestions.length) {
    testStatus.innerHTML = "Test Completed";
    test.innerHTML = "<h2>" + "You got " + correct + " out of " + allQuestions.length + "</h2><br/>";
    pos = 0;
    return false
};
testStatus.innerHTML = "Question " + (pos + 1) + " of " + allQuestions.length;
var A = allQuestions[pos].choices[0];;
var B = allQuestions[pos].choices[1];;
var C = allQuestions[pos].choices[2];
test.innerHTML = "<h2>" + allQuestions[pos].question + "</h2><br/>";
for (var j = 0; j < 3; j++) {
    var letter = null;
    switch (j) {
        case 0:
            letter = "A";
            break;
        case 1:
            letter = "B";
            break;
        case 2:
            letter = "C";
            break;
    }
    if (savedAnswers[pos] == j) {
        test.innerHTML += '<input type="radio" checked="true" value="' + letter + '" name="answerswerChoice" /> ' + letter + '<br />';
    } else {
        test.innerHTML += '<input type="radio" value="' + letter + '" name="answerswerChoice" /> ' + letter + '<br />';
    }
}
//test.innerHTML += '<input type="radio" value="A" name="answerswerChoice" /> ' + A + '<br />';
//test.innerHTML += '<input type="radio" value="B" name="answerswerChoice" /> ' + B + '<br />';
//test.innerHTML += '<input type="radio" value="C" name="answerswerChoice" /> ' + C + '<br /><br />';
if (pos == allQuestions.length - 1) {
    test.innerHTML += '<input type="button" id="next" onclick="prevAnswer()" value="Prev"> ';
    test.innerHTML += '<input type="button" id="next" onclick="checkAnswer()" value="Submit"> ';
} else if (pos >= 1) {
    test.innerHTML += '<input type="button" id="next" onclick="prevAnswer()" value="Prev"> ';
    test.innerHTML += '<input type="button" id="next" onclick="checkAnswer()" value="Next"> ';
} else {
    test.innerHTML += '<input type="button" id="next" onclick="checkAnswer()" value="Next"> ';
}
test.innerHTML += '<br /><br /><p id="error"></p>'

}