In a callback, I open tabs like this:

1.           $('#packageTable tbody').on( 'click', 'button', function () {
2.             var data = table.row($(this).parents('tr')).data();
3.             var tabId = "tab-" + data.id;
4.             $("<li id=" + tabId + "><a href='" + tabId + "'>" + data.package + "</a</li>")
5.                 .appendTo("#tabs .ui-tabs-nav");
6.             $("#tabs").tabs("refresh");
7.         });

In other words: The tabs have an associated id. (The tabId.) Now, I'd like to change the callback as follows:

Check, if a tab with the given id is already open. If so, do nothing. Otherwise, create the new tab.

How would I do that?

Thanks,

Jochen