Select operations in jquery Firefox3.5

There is a select element on the page with the id of customer. Many Methods on the Internet that introduce jquery to reference the selected value of select are used:
Copy codeThe Code is as follows:
$ ("# Customer option [selected]"). val ();


This method is used to obtain the value of the selected selcte. I have always used this method, but I recently installed the official FF3.5 version. I found that this method is not worth the value below, so I went to view the help document of jquery, the following method is used to reference the selected select statement in this document:

Copy codeThe Code is as follows:
$ ("# Customer option: selected"). val ();


It is normal to reference it in FF3.5 using this method.