javascript - Javascript 中的返回值和变量范围

Question

我在弄清楚如何在一个函数中正确返回一个值并将其传递给另一个函数时遇到一些麻烦。变量是 randomQuestion，我无法让它以整数形式出现在函数中。这个想法是在两个函数中使用相同的问题 ID，因此例如在第二个函数中，我可以使用它来确定提出的问题，并找到正确的答案以将其与用户输入相匹配。

$('#quiz').on('click', beginQuiz);
$('#giveanswer').on('click', nextQuestion);

var randomQuestion = Math.floor(Math.random() * questions.length);

function beginQuiz(randomQuestion) {

    $("#questions tbody tr").remove();
    document.getElementById("questions").deleteTHead();

    //Get the JSON data from our HTML and convert it to a JavaScript object
    //In the real world, this data will likely be retrieved  from the server via an AJAX request
    var questions = JSON.parse(document.getElementById('questions-json').innerHTML);



    console.log(randomQuestion);

    var quizQuestion = questions[randomQuestion];


    var tblRow = '<tr>' + '<td>' + quizQuestion.q_text + '</td>' + '</tr>'
        //Add our table row to the 'questions' <table>
    $(tblRow).appendTo('#questions tbody');

    document.getElementById('answers').style.display = 'block';
    document.getElementById('answerlabel1').innerHTML = quizQuestion.q_options_1;
    document.getElementById('answerlabel2').innerHTML = quizQuestion.q_options_2;
    document.getElementById('answerlabel3').innerHTML = quizQuestion.q_options_3;
    document.getElementById('answerlabel4').innerHTML = quizQuestion.q_options_4;

    return randomQuestion;
}

function nextQuestion(randomQuestion) {

    console.log(randomQuestion);
    //Get the JSON data from our HTML and convert it to a JavaScript object
    //In the real world, this data will likely be retrieved  from the server via an AJAX request
    var questions = JSON.parse(document.getElementById('questions-json').innerHTML);
    var score = 0;
    var playeranswer = $('input:radio[name=answer]:checked').val();
    var correctanswer = questions[randomQuestion].q_correct_option;

    if (playeranswer == questions.q_correct_option) {
        score++
        document.getElementById('score').innerHTML = score;
    }
}

Answer 1

从两个函数声明中删除 randomQuestion 参数，因为它是全局的。正如所写，您的两个函数都会查看自己的本地 raqndomQuestion 变量，该变量未定义。