为什么单击鼠标后看不到动态创建的按钮上的数据字段？

Question

Edit: Here is a JSFiddle which displays the problem I'm having:

http://jsfiddle.net/gyhvpmgy/4/

---

I have the following function creating a dynamic div:

InvalidField.prototype.getMessageStructure = function(){
    var div = $('<div></div>').addClass('invalidRow');      
    var span = $('<span></span>')
        .text(this._message)
    var button = $('<button></button>')
        .addClass('btn_AlertFocus')
        .text("Go To Field")
        .data("field", this._field[0].name)    

    return div.append(button).append(span);
};

Prior to the return line, through debugging I can see that button.data('field') contains, as it should: "applicant.email".

I also have the following generic button click event:

$(document).on('click', '.btn_AlertFocus', function() {
    var field = $(this).data('field');
    goToFieldFromAlert('input[name="' + field + '"]');
});

'field' is now coming up as undefined.

Is anyone able to tell me why, it will probably be something obvious - this is a new feature to me?

Below is the snippet that takes this returned string value.

function validateForm(){
    if(list_Invalid.size() > 0){
        var structure = "";
        for ( i = 0; i < list_Invalid.size(); i ++){
            structure += list_Invalid.item(i).getMessageStructure()[0].outerHTML;
        }
        var alert = new Alert(structure, 
                function(){
                }
            ).showAlert();      
        return false;
    }
    return true;
}

Many thanks!

Answer 1

jQuery uses an internal representation for working with data .

If you initially had a data attribute on an HTML element, then doing $('foo').data('bar') would cause jQuery reading the attribute into memory. Further working with that data , modifying it, will not cause the attribute to change.

If you didn't have the attribute in the first place, then jQuery would work with data in memory, and the attribute will never appear in HTML.

To explicitly update the HTML attribute, use this:

$('foo').attr('data-bar', 'value');

But it's slower and converts the value into a string.