使用AJAX后，我无法调用onclick javascript函数

Question

I'm totally newbie in javascript/jQuery and i have a little problem :)

I'm using AJAX to get datas to generate and populate form fields. After that, i would like to add and/or remove fields with javascript functions but it doesn't work.

As i'm learning, i make my code step by step, so the following code implement the ajax request (which is working perfectly), and the function which i would like to call with an on click attribute on an + image.

$(document).ready(function(){

var id = $('#subId').val();
var num     = $('.cloneSub').length;
var newNum  = new Number(num + 1);

$.ajax({
    type: 'POST',
    dataType: 'json',
    url: '/admin/popsub2/',
    data: 'id='+id,
    async: false,
    success: function(data){

        $.each(data, function(key, val){

            // Add and populate the input text element
            var newElem = $('#sub' + num).clone().attr('id', 'sub' + newNum);
            newElem.children(':first').attr('id', 'sub' + newNum).attr('name', 'sub' + newNum);

            $('#sub' + num).attr('value', val);

            $('#sub' + num).after(newElem);
            $(newElem).before('<br />');

            // Simply add the select element
            var newSelect = $('#editMenu_article' + num).clone().attr('id', 'editMenu_article' + newNum);
            newSelect.children(':first').attr('id', 'editMenu_article' + newNum).attr('name', 'editMenu_article' + newNum);

            $('#editMenu_article' + num).after(newSelect);
            $(newSelect).before('<br />');
        });
    },

    failure: function(){
        alert('echec !!!');
    }
});


function addField(){

    // Add the input text element
    var newElem = $('#sub' + num).clone().attr('id', 'sub' + newNum);
    newElem.children(':first').attr('id', 'sub' + newNum).attr('name', 'sub' + newNum);

    $('#sub' + num).attr('value', val);

    $('#sub' + num).after(newElem);
    $(newElem).before('<br />');

    // Add the select element
    var newSelect = $('#addMenu_article' + num).clone().attr('id', 'addMenu_article' + newNum);
    newSelect.children(':first').attr('id', 'addMenu_article' + newNum).attr('name', 'addMenu_article' + newNum);

    $('#addMenu_article' + num).after(newSelect);
    $(newSelect).before('<br />');

}

});

The addField() function doesn't work at all, and i don't know why. AJAX seems to keep a hand on the script execution.

Thanx for your help.

UPDATE

My + image is :

<img src="images/plus.png" id="editSub2" />

Following your help i tried those codes :

$('#editSub2').live('click', function(){ ... });

$('#editSub2').bind('click', function(){ ... });

But nothing works.

Answer 1

You've declared addField() inside the scope of your jQuery document ready callback. No one outside that function will be able to know about it. You can declare it as a global function, but you'll be better encapsulating it. You might find something like Javascript Patterns a helpful resource.

Answer 2

If the image is created dynamically, you should bind the click event after creating it, if not, on the document ready block, you must bind it.

$('img#myimg').bind("click", function(){

// Add the input text element
    var newElem = $('#sub' + num).clone().attr('id', 'sub' + newNum);
    newElem.children(':first').attr('id', 'sub' + newNum).attr('name', 'sub' + newNum);

    $('#sub' + num).attr('value', val);

    $('#sub' + num).after(newElem);
    $(newElem).before('<br />');

    // Add the select element
    var newSelect = $('#addMenu_article' + num).clone().attr('id', 'addMenu_article' + newNum);
    newSelect.children(':first').attr('id', 'addMenu_article' + newNum).attr('name', 'addMenu_article' + newNum);

    $('#addMenu_article' + num).after(newSelect);
    $(newSelect).before('<br />');


});

Answer 3

Sounds like you've run into the DOM event handler trap. This issue makes more sense if you've ever handled events sans jQuery.

Basically, what happens when you do this:

$(".images").click(myFunc);

is that jQuery goes and finds all elements that match the selector and binds the function myFunc to the onclick event, using this (roughly) code:

element.onclick = myFunc;

(It actually does something more complicated, but just assume that thats what it does)

and that happens when you run the above code and only then, any extra elements added to the DOM don't have that event added, jQuery was never told to add them!

However, all is not lost, you can use the brilliant .live() function in jQuery to bind to all matching elements, existing and future. Its simpler and easier to use than having to manually rebind new elements and less error prone. One minor downside is that it interferes with event ordering, and you have to use a .bind() -like interface, so you use .live("click", myfunc) instead.

EDIT

In light of reading more of your question, it seems that the problem is that you have is that you have bound to #editSub2 but are generating #editSub<n> so jQuery has no idea what you are on about. I suggest using classes to push common functionality onto elements, and IDs for unique elements, for one its probably more efficient.