javascript - 将事件处理程序添加到不存在的类中？

Question

我见过与不存在的元素相关的问题，但与不存在的类无关。这就是我想做的。当单击“see_answer”类的按钮时，我想删除该类并将其替换为“see_question”。但是，一旦按钮的类为“see_question”，我的单击函数就不会运行。我已经尝试过 $(document).on("click", ".see_question", function(event ) 并且我已经尝试过 $(".see_question").on("click", function(event) {etc...。感谢您的帮助!我的代码如下:

$(document).ready(function() {

// initialize variables
var lang = "javascript";
var qno = 1;
var prevText;       // holds question/answer
var language = lang + ".html";


// set up tabs, and keep track of which one is clicked
$("#myTabs").tabs({
    activate: function (event, ui) {
        var active = $("#myTabs").tabs("option", "active");
        lang = $("#myTabs ul > li a").eq(active).attr("href"); 
        lang = lang.replace("#", "");
    }
});

/* REMINDERS
    actual qa part: blah_language
*/

// set up question
$.ajax({
    url: language,
    dataType: "html",
    success: function(data) {
    $("#blah_"+lang)
    .text($(data).find("#1").text());
    },
    error: function(r) {
        alert("whoops, error in initialization");
    }
});


$(".next_question").on("click", function(event) {

    event.preventDefault();

    var id = $(this).attr("id").replace("next_question_", "");

    var language = id + ".html";
    var doc = "#blah_" + id;

    $.ajax({
        url: language,
        dataType: "html",
        success: function(data) {
            var num = "#" + qno;
            $(doc)
            .text($(data).find(num).text());
            qno = qno + 1;

        },
        error: function(r) {
            alert("whoops");
        }
    });
    prevText = "";
});



// SHOW ANSWER
$(".see_answer").on("click", function(event) {
    event.preventDefault();
    var id = $(this).attr("id").replace("see_answer_", "");
    var prev = "#blah_" + id;
    var answers = id + "_answers.html";


    // Save the question
    prevText = $(prev).text();
    var obj = $(this);

    $.ajax({
        url: answers,
        dataType: "html",
        success: function(data) {
            var num = "#" + 3;
            $(prev)
                .text($(data).find(num).text());
        },
        error: function(r) {
            alert("whoops");
        }
    });

    obj.val("See Question");
    obj.removeClass("see_answer");
    obj.addClass("see_question");
    event.stopPropagation();

});

$(document).on("click",".see_question",  function(event) {
    event.preventDefault();
        obj = $(this);
    event.preventDefault();
    var id = $(this).attr("id").replace("see_answer_", "");
    var prev = "#blah_" + id;
    $(prev).text(prevText);

    obj.val("See Answer");

    obj.removeClass("see_question");
    obj.addClass("see_answer");

});

})

Answer 1

.see_question 元素的点击处理委托(delegate)给 document。对于 .see_answer 元素，直接附加点击处理程序。因此，交换类名将会产生不良效果。

• 当 see_answer 生效时，点击将触发“see_answer”处理程序。
• 当 see_question 生效时，点击将触发“see_question”处理程序和“see_answer”处理程序，仍然附加。

有多种方法可以正确地做到这一点。从您当前的位置来看，最简单的解决方案是将 .see_question 和 .see_answer 元素的点击处理委托(delegate)给 document.

$(document).on("click", ".see_answer", function(event) {
    ...
});

$(document).on("click", ".see_question", function(event) {
    ...
});