Question

为什么在for for循环迭代第一个答案对象数组后，click方法返回undefined？

var i = 0;
var j = 0;

var allQuestions = [{question:"What is the color of the sky?",answer:["blue","yellow",  
                "red"],correctAnswer:["blue",1]},{question:"What is the opposite of  
                 up?",answer:["down","sideways", "circle"],correctAnswer:["down",1]},
                {question:"What is the first number?",answer:["1","5", "7"],correctAnswer:
                ["1",1]}];

$(document).ready(function() {  

    function changeQuestion() {
        $("#radios").empty();
        for( answers in allQuestions[i].answer) {
            var radioBtn = $('<input type="radio" class="radios" name="btnAnswers" value="'+ 
                allQuestions[i].answer[j] + '" /><label for ="secondbtn">'
                + allQuestions[i].answer[j] + '</label>');
            radioBtn.appendTo('#radios');
            alert(allQuestions[i].answer[j]);
            j++;
        }
        i++;
        return true;
    };

    $("#nextbtn").click(function(){
        changeQuestion();
    });
});

This question's fiddle

Answer 1

由于对象的.answer属性是一个数组，您可以使用

循环

for(var j=0; allQuestions[i].answer.length; j++) {...}

而不是

for(answers in allQuestions[i].answer) {...}

完整代码将是：

$(document).ready(function() {
    var i = 0;
    function changeQuestion() {
        $("#radios").empty();
        var obj = allQuestions[i];
        for(var j=0; j<obj.answer.length; j++) {
            $('<input type="radio" class="radios" name="btnAnswers" value="' + obj.answer[j] + '" /><label for ="secondbtn">' + obj.answer[j] + '</label>').appendTo('#radios');
        }
        i++;
    };
    $("#nextbtn").click(changeQuestion);
});

https://jsfiddle.net/zu9e5poh/10/

Answer 2

你必须将值初始化为变量i＆amp; Ĵ

将代码修改为

    $(document).ready(function() {  
function changeQuestion() {
$("#radios").empty();

var  i=0, j=0;

for( answers in allQuestions[i].answer) {
    var radioBtn = $('<input type="radio" class="radios" name="btnAnswers" value="'+ 
                    allQuestions[i].answer[j] + '" /><label for ="secondbtn">' 
            + allQuestions[i].answer[j] + '</label>');
    radioBtn.appendTo('#radios');
    alert(allQuestions[i].answer[j]);
 j++;
}
 i++;
 return true;
};
$("#nextbtn").click(function(){
    changeQuestion();
 });

}）;

jQuery click方法在迭代嵌套在另一个数组中的对象中的数组时返回undefined

2 个答案: