jQuery attr('id') returns undefined
Question
I have a list of items and when a user clicks on one of them, it gets assigned a class called 'active-child'. Just one item could be selected at the moment, and when the user clicks on another item, this item is cleaned of 'active-child' class and then this class gets assigned to the newly selected item. Just like any other non-multiple list.
Here is the selected element's HTML:
<div id="5" class="new-child-item new-child-item-active active-child"> Software </div>
When I want to submit the selected item's "id" to a php script to process it further, the jquery does not retrieve the id value of the element and says it is undefined . My approach to getting the selected item's id attribute is as follows:
$('.active-child').attr('id');
I also have tested this, but still returns undefined :
$('.active-child:first-child').attr('id');
The strange thing is that I first check to see if the user has selected anything at all, and if yes, then do the ajax, at this moment, the jquery returns 1 , means the user has selected one item. Here is the code block which checks to see the selection and then send it through ajax:
if($('.active-child').length > 0)
{
$('.new-item-cats-list-holder').empty();
$('.new-item-cats-list-holder').hide()
$('.big-loader').show();
console.log("This is the id: " + $('.new-child-item-active:first-child').attr('id'));
$.ajax({
url : base_path('ajax/set_credentials/step_2'),
type: "POST",
data : ({'set_sess':true, 'category' : $('.active-child').attr('id')}),
success : function(msg){
if(msg!=0)
{
//window.location.href = base_path('panel/add/step/ads/3');
}
},
});
}// end of length if
2 answers
solution1
1
在ID检索销毁和DOM之前，empty（）和hide（）函数起作用，并且不允许它存在，然后再获取其id值。
solution2
0 2014-01-01 15:34:26
I have an inkling that you are using numerical values as IDs, or at least have ID that starts with a number. My suspicion comes from the fact that your console log returns 1, and you have specified in your question that you are logging the active child's ID.
This is invalid — classes and IDs have to start with an alphabet or an underscore or a dash, and then followed by any alphanumeric, underscore or dash characters and a combination thereof.
See here: Which characters are valid in CSS class names/selectors? and http://www.w3.org/TR/CSS21/syndata.html#characters
This is unless you are using HTML5, but you need to declare the doctype correctly: <!DOCTYPE html>
Also, have you checked that your IDs are unique?
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