Question

我有一个数组，可以解答给定问题的学生答案。

如果学生给出答案，它会被插入到当前索引的数组中，如[ "answer", undefined, // student has not given answer "answer2", ]

之后，我可以读取数组并将条目映射到给定的问题数组

这种情况：

if (answers[questionindex] === undefined)

的工作原理。（循环遍历数组，只输出“没有给出答案”undefined

但是当LAST答案未定义（1个或更多）时它不起作用他们只是不存在（当然）。

如何将这些字段设置为var testResults = { addRoom: function(Id, teacher) { // room pseudoconstructor this[Id] = { created: moment(), runningProblem: false, time: 0, // holds the countdown for the current problem getTime: function() { // returns the countdown-counter return this.time; }, Id: Id, teacher: teacher, getCurrentSolution: function() { return math.eval(this.testProblems[this.getCurrentProblemIndex()].problem); }, getTimeTaken: function() { return this.getCurrentProblemTimeLimit() - this.time; }, getCurrentProblemTimeLimit: function() { return this.testProblems[this.getCurrentProblemIndex()].timeLimit; }, getCurrentProblemIndex: function() { return this.testProblems.length - 1; }, addTestProblem: function(problem, timeLimit) { var solution = math.eval(problem); this.testProblems.push({problem: problem, timeLimit: timeLimit, solution: solution}); console.dir(this.testProblems); }, testProblems: [], updatePercentages: function(name) { function round(num) { return +(Math.round(num + "e+2") + "e-2"); } console.log('updating percentages'); console.log('answers length ' + this.students[name].givenAnswers.length); var timeSum = 0; for(var i = 0; i < this.students[name].givenAnswers.length; i++ ) { timeSum += this.students[name].givenAnswers[i].takenTime; } var timeAvg = timeSum / this.students[name].givenAnswers.length; console.log('timeAvg for ' + name + ' ' + timeAvg); this.students[name].avgTime = round(timeAvg); var correctSum = 0; for(var j = 0; j < this.students[name].givenAnswers.length; j++ ) { if (this.students[name].givenAnswers[j].correct) { correctSum++; } } var correctAvg = correctSum / this.students[name].givenAnswers.length; console.log('correctAvg for ' + name + ' ' + correctAvg); this.students[name].avgCorrect = round(correctAvg) * 100; }, addGivenStudentAnswer: function(name, answer, takenTime, index) { console.log('adding answer ' + name + ' ' +answer+ ' ' + takenTime); var correct = this.getCurrentSolution() == answer; if (typeof this.students[name].givenAnswers[index] === 'undefined') { this.students[name].givenAnswers[index] = ({ answer: answer, takenTime: takenTime, correct: correct }); this.updatePercentages(name); //console.dir(this.students[name].givenAnswers); return true; } else { console.log('attempt at double answer. not saved'); return false; } }, addStudent: function(name) { if (!(this.students[name])) { this.students[name] = { studentName : name, avgTime: 0, avgCorrect: 0, givenAnswers: [] } } console.dir(this); }, students: {} }; console.dir(this); }, deleteRoom: function(Id) { delete this[Id]; console.log('room deleted from testResults'); } };（例如，在计时器达到零之后），以显示没有给出答案？

现在，平均值计算显示3个给定（正确）的100％正确，然后2个未给出

码

// after test

router.get('/showtests/:roomId', function(req, res) {
    if (req.user && req.user.role === 'teacher') {
        tests.findOne({roomId: req.params.roomId}, {}, function(err, result) {
            if (err) {console.log(err);}
            res.render('showSingleTest', {user: req.user, testData: JSON.parse(JSON.stringify(result))});
        })
    } else {
        res.render('customerror', { title: "Error", errMsg1: "error.error", errMsg2: "error.notLoggedIn" });
    }
});

从DB afterwars读取测试的路线

h2(data-i18n="markup.studentsAnswers")
each student in testData.students
    .testViewSingleStudentAnswers.col-md-6
        h3 #{student.studentName}

        ol.answers
            each answer in student.givenAnswers
                if (answer)
                    if (answer.correct == true)
                        li.correct
                            span #{answer.answer}
                            | &nbsp;&nbsp;&nbsp;
                            span.floatRight (#{answer.takenTime}s)
                    else
                        li.wrong
                            span #{answer.answer}
                            | &nbsp;&nbsp;&nbsp;
                            span.floatRight (#{answer.takenTime}s)
                else
                    li.noAnswer(data-i18n="markup.noAnswerGiven")
        .testTotals
            | #{student.avgCorrect}
            span(data-i18n="markup.percentCorrect")
            | ,&nbsp;
            | #{student.avgTime}
            span(data-i18n="markup.avgTime")

aaaaa和玉

{{1}}

Answer 1

你可以这样做：

function push_answer(answer){
answer = answer || "undefined"
array_of_answers.push(answer)
}

现在，该值未定义，但由文字定义。你可以用一些unicode字符替换它，以防某些答案可以是＆＃34; undefined＆＃34;。

度过美好的一天！

Answer 2

似乎对我没有问题。

HTML：

<div id="content">

</div>

JS：

var answers = ["answer1","answer2",undefined,"answer3",undefined];

for(i=0;i<answers.length;i++) {
  if(!answers[i]){
    answers[i]="no answer";
  }
}
document.getElementById('content').innerHTML = answers;

jsFiddle

Answer 3

我的个人推荐：＆＃34;永远不要把事情弄清楚＆＃34;

如果学生没有选择答案，你应该用“＆＃39;”填充该空白区域，因为未定义真的很难处理，所以为了填补空白：

这将检查答案是否为＆＃34;未定义＆＃34;用＆＃39;填补空白（空白），然后，当你检查答案时，评估会更简单......

Sub taskupdateMacro(item As Outlook.MailItem)

 Dim olkApp, olkNS, olkTaskFolder, objItem, olkTaskUpdate, olkTask
 Dim objCount
 objCount = 0

 Set olkApp = CreateObject("Outlook.Application")
 Set olkNS = olkApp.GetNamespace("MAPI")
 olkNS.Logon "Outlook"
 Set olkTaskFolder = olkNS.GetDefaultFolder(6)
 For Each objItem In olkTaskFolder.Items
     If (objItem.Class = 50 Or objItem.Class = 51 Or objItem.Class = 43) Then
        objCount = objCount + 1
        objItem.Display
        objItem.Close 1
     End If
 Next

 If objCount = 0 Then
    MsgBox "No Task Related Emails to Open"
 End If

 Set objItem = Nothing
 Set olkTaskFolder = Nothing
 Set olkTaskRequest = Nothing
 Set olkTask = Nothing
 olkNS.Logoff
 Set olkNS = Nothing
 Set olkApp = Nothing

End Sub

设置空数组索引

3 个答案: