Additional WHERE tabs - Retrieve active tab id

For inspiration see this jsfiddle : http://jsfiddle.net/Lv5VJ/2/

Here is the Javascript code that returns the ID of the active WHERE tab:

I have put the following in the JavaScript OnLoad event but the alert box is displaying 'undefined'
//Get Active TAB ID

var ActiveTABID = $("li[class=active]").find("a").attr("data-tabid");

alert(ActiveTABID);

Your code works here.

I don't understand why my code won't work.

I have reset the page and tried again, but i am still getting the 'undefined' message

As an alternative you can read "tab" parameter from the URL. This article can help:

https://stackoverflow.com/questions/979975/how-to-get-the-value-from-the-get-parameters

I am using this currently to determine the current tab, but i came across a few issues with this which resulted in me asking my original question.
When a user clicks on a column to sort the records or uses the search function the url changes from

/dbo_tAppointment_Record_list.php?tab=1008

to

/dbo_tAppointment_Record_list.php?orderby=dApptDate
...and when you initially land on a page with 'Additonal WHERE tabs' there is no 'tab=????' in the url until you click on another tab and then click back.

After you read tab id from the URL save it in session variable and use it in subsequent page calls till new one appears in the URL.