To get the contents of the attribute data-id
(like in <a data-id="123">link</a>
) you have to use
$(this).attr("data-id") // will return the string "123"
or .data()
(if you use newer jQuery >= 1.4.3)
$(this).data("id") // will return the number 123
and the part after data-
must be lowercase, e.g. data-idNum
will not work, but data-idnum
will.