Question

我试图弄清楚我的脚本中的错误，并希望有人能够告诉我哪里出错了。这是尝试基于JS / Jquery（javascriptissexy练习）创建测验。

到目前为止它工作正常，除了：我想使用后退按钮来回忆用户先前给出的答案并相应地设置单选按钮。该脚本不会返回，即使我点击它，也没有任何错误可以帮助我查明问题。

我再次感到非常抱歉，我无法将其缩小范围，因为我真的不知道哪些部分相关/不相关。如果有人有一些建议如何呈现那些“我已经接近放弃，因为我不知道如何找出问题”的问题以更好的方式我会很乐意这样做。

HTML单选按钮的结构如下：

 <input type="radio" name="radio" id="Option0" value="Option0" />
 <label for ="Option0">Option0</label>

JS / Jquery：

 $(document).ready(function () {
 var allQuestions = [
    {question: "Who is Prime Minister of the United Kingdom?",
        choices: ["David Cameron", "Gordon Brown", "Winston Churchill", "Tony Blair"],
        correctAnswer: 0},
    {question: "Which color has the sky?",
        choices: ["Grey", "Black", "Blue", "Green"],
        correctAnswer: 2},
    {question: "What's on the chain?",
        choices: ["Monster", "Magician", "Bull", "Skull"],
        correctAnswer: 3}
];

var counter = 0;     // Question No currently processed
var points = 0;        // Total points currently reached by the player
var answers = new Array(); // Array of the choices the player made  eg Q1:0

// Back button in a function
function back() {
    if (counter > 0)          //Checks if there is at least one question already answered
    {
        //Goes back one question

        $("#back").show().on('click', function () {
            counter = counter--;
            quiz();
        });      //Executes quiz loading

    }
    else {
        $("#back").hide();         //If there is no previous question existing the back button is deactivated
    }
}


function qload(counter) {
    $("title").text("Question No ");
    $("#question").text(allQuestions[counter].question);
    back();
    for (var i = 0; i < allQuestions[counter].choices.length; i++) {
        $('label[for=Option' + i + ']').html(allQuestions[counter].choices[i]);

        if (answers["Q" + i]) {
            $("#Option" + i).attr("checked","checked");
        }

        else {
            $("#Option" + i).removeAttr('checked');
        }
    }
};
//this is the result screen giving the final amount of points
function result() {
    $("title").text("Your Results");
    for (var i = 0; i < allQuestions.length; i++) {
        if (allQuestions[i].correctAnswer == answers["Q" + i]) {
            points++;
        }


        $("#result").show().text("CONGRATULATIONS! You answered " + points + " out of " + allQuestions.length + " correct!");
        $(".qbox").hide();
        console.log(answers);

    }
}

function welcome() {
    // this is the welcome screen inviting to start the quizz
    $("title").text("Welcome to the JQuery QuizY");
    $(".qbox").hide();
    $("#result").append().html("Random");
    $("#result").append().html("<p id='start'>Start</p>");
    $("#start").on('click', function () {
        quiz();
    });
}

function quiz() {
    $("#start, #result").hide();
    $(".qbox").show();
    qload(counter);
    $("#next").on('click', function () {
        // this checks that one question is selected before processing
        if ($('#Option0').is(':checked')) {
            answers["Q" + counter] = 0;
            counter++;
        }

        else if ($('#Option1').is(':checked')) {
            answers["Q" + counter] = 1;
            counter++;
        }

        else if ($('#Option2').is(':checked')) {
            answers["Q" + counter] = 2;
            counter++;
        }

        else if ($('#Option3').is(':checked')) {
            answers["Q" + counter] = 3;
            counter++;
        }

        else {
            alert("Please make your selection before continuing!");
        }

        // this checks if there are any questions left, otherwise it goes to the result screen
        if (allQuestions[counter]) {
            qload(counter);
        }
        else {
            result();
        }
    });
}

welcome();

});

Answer 1

1）您不能通过使用字符串作为索引来引用数组元素（answers [“Q”+ i]）。您必须使用数字作为数组索引，或使用对象而不是数组。

2）不要使用.attr（）方法修改DOM属性，例如“checked”。请改用.prop()方法。所以你必须替换这个片段：

if (answers["Q" + i]) {
    $("#Option" + i).attr("checked","checked");
}

else {
    $("#Option" + i).removeAttr('checked');
}

以下内容：

$("#Option" + i).prop("checked", Boolean(answers["Q" + i]));

3）获得用户答案价值的方式非常麻烦而且很奇怪。这段代码：

    if ($('#Option0').is(':checked')) {
        answers["Q" + counter] = 0;
        counter++;
    }

    else if ($('#Option1').is(':checked')) {
        answers["Q" + counter] = 1;
        counter++;
    }

    else if ($('#Option2').is(':checked')) {
        answers["Q" + counter] = 2;
        counter++;
    }

    else if ($('#Option3').is(':checked')) {
        answers["Q" + counter] = 3;
        counter++;
    }

    else {
        alert("Please make your selection before continuing!");
    }

可以替换为以下内容：

var oEl = $('input:radio[name=radio]:checked');
if (oEl.length) {
    answers[counter] = parseInt(oEl.val());
    counter++;
}
else {
    alert("Please make your selection before continuing!");
}

还需要以下修复单选按钮的html代码：

<input type="radio" name="radio" id="Option0" value="0" />
<label for ="Option0">Option0</label>

加上其他一些改变......

总代码更新：

$(document).ready(function () {
var allQuestions = [
    {question: "Who is Prime Minister of the United Kingdom?",
        choices: ["David Cameron", "Gordon Brown", "Winston Churchill", "Tony Blair"],
        correctAnswer: 0},
    {question: "Which color has the sky?",
        choices: ["Grey", "Black", "Blue", "Green"],
        correctAnswer: 2},
    {question: "What's on the chain?",
        choices: ["Monster", "Magician", "Bull", "Skull"],
        correctAnswer: 3}
];

var counter = 0; // Question No. currently processed
var answers = new Array(); // Array of the choices the player made

$('#back').click(function(){
    counter++;
    quiz();
});

// update Back button appearance
function updateBackBtn() {
    if (counter > 0)
        $("#back").show();
    else
        $("#back").hide();
}

// set current question
function qload(counter) {
    $("title").text("Question No ");
    $("#question").text(allQuestions[counter].question);
    updateBackBtn();
    for (var i = 0; i < allQuestions[counter].choices.length; i++) {
        $('label[for=Option' + i + ']').html(allQuestions[counter].choices[i]);

        $("#Option" + i).prop("checked", Boolean(answers[i]));
    }
};

// this is the result screen giving the final amount of points
function result() {
    $("title").text("Your Results");
        var points = 0; // Total points currently reached by the player
    for (var i = 0; i < allQuestions.length; i++) {
        if (allQuestions[i].correctAnswer == answers[i]) {
            points++;
        }
        $("#result").show().text("CONGRATULATIONS! You answered " + points + " out of " + allQuestions.length + " correct!");
        $(".qbox").hide();
        console.log(answers);

    }
}

function welcome() {
    // this is the welcome screen inviting to start the quizz
    $("title").text("Welcome to the JQuery QuizY");
    $(".qbox").hide();
    $("#result").append().html("Random");
    $("#result").append().html("<p id='start'>Start</p>");
    $("#start").on('click', function () {
        quiz();
    });
}

function quiz() {
    $("#start, #result").hide();
    $(".qbox").show();
    qload(counter);
    $("#next").on('click', function () {
        // get an input element containing selected option (answer)
        var oEl = $('input:radio[name=radio]:checked');
        // if such input element exists (any answer selected)
        if (oEl.length) {
            answers[counter] = parseInt(oEl.val());
            counter++;
        }
        else {
            alert("Please make your selection before continuing!");
        }

        // this checks if there are any questions left, otherwise it goes to the result screen
        if (counter < allQuestions.length) {
            qload(counter);
        }
        else {
            result();
        }
    });
}

welcome();

});

Answer 2

我已经完成了代码并且没有做任何挑衅。

请查看以下更新的代码。

$(document).ready(function () {
                var allQuestions = [
                    {question: "Who is Prime Minister of the United Kingdom?",
                        choices: ["David Cameron", "Gordon Brown", "Winston Churchill", "Tony Blair"],
                        correctAnswer: 0},
                    {question: "Which color has the sky?",
                        choices: ["Grey", "Black", "Blue", "Green"],
                        correctAnswer: 2},
                    {question: "What's on the chain?",
                        choices: ["Monster", "Magician", "Bull", "Skull"],
                        correctAnswer: 3}
                ];

                var counter = 0;     // Question No currently processed
                var points = 0;        // Total points currently reached by the player
                var answers = new Array(); // Array of the choices the player made  eg Q1:0

                // Back button in a function
                function back() {
                    if (counter > 0)          //Checks if there is at least one question already answered
                    {
                        $("#back").show();
                    }
                    else {
                        $("#back").hide();         //If there is no previous question existing the back button is deactivated
                    }
                }

                $('#back').click(function(){
                    counter = --counter;
                    quiz();//Executes quiz loading
                });

                function qload(counter) {
                    $("#title").html("Question No "+counter);
                    $("#question").text(allQuestions[counter].question);
                    back();
                    for (var i = 0; i < allQuestions[counter].choices.length; i++) {
                        $('label[for=Option' + i + ']').html(allQuestions[counter].choices[i]);
                        if (answers["Q" + counter] == i) {
                            $("#Option" + i).prop('checked',true);
                        }

                        else {
                            $("#Option" + i).removeAttr('checked');
                        }
                    }
                };

                //this is the result screen giving the final amount of points
                function result() {
                    $("#title").html("Your Results");
                    for (var i = 0; i < allQuestions.length; i++) {
                        if (allQuestions[i].correctAnswer == answers["Q" + i]) {
                            points++;
                        }


                        $("#result").show().text("CONGRATULATIONS! You answered " + points + " out of " + allQuestions.length + " correct!");
                        $(".qbox").hide();
                        console.log(answers);

                    }
                }

                function welcome() {
                    // this is the welcome screen inviting to start the quizz
                    $("title").html("Welcome to the JQuery QuizY");
                    $(".qbox").hide();
                    $("#result").append().html("Random");
                    $("#result").append().html("<p id='start'>Start</p>");
                    $("#start").on('click', function () {
                        quiz();
                    });
                }

                function quiz() {
                    $("#start, #result").hide();
                    $(".qbox").show();
                    qload(counter);
                }
                $("#next").click(function () {
                    // this checks that one question is selected before processing
                    if ($('#Option0').is(':checked')) {
                        answers["Q" + counter] = 0;
                        ++counter;
                    }

                    else if ($('#Option1').is(':checked')) {
                        answers["Q" + counter] = 1;
                        ++counter;
                    }

                    else if ($('#Option2').is(':checked')) {
                        answers["Q" + counter] = 2;
                        ++counter;
                    }

                    else if ($('#Option3').is(':checked')) {
                        answers["Q" + counter] = 3;
                        ++counter;
                    }

                    else {
                        alert("Please make your selection before continuing!");
                    }

                    // this checks if there are any questions left, otherwise it goes to the result screen
                    if (allQuestions[counter]) {
                        qload(counter);
                    }
                    else {
                        result();
                    }
                });

                welcome();

            });

我已经进行了上述更改，并在我的本地进行了测试，但它确实有效。

如果您遇到任何问题，请与我们联系。

JQuery：检查/取消选中单选按钮

2 个答案: