[jQuery] To check if an element value is of a particular class type

[Santo]

Hello All

This is what I am trying to do. I have defined an "email suffix" class
for a particular textbox element so that it accepts values for that
particular class. Whenever there is a different value inserted, it
displays a jquery error. Now, there also is an Add button which should
add the value and display it in a widget list if it is a "valid
value".

So, I need to check and insert an if else block on the click event of
the add button to check if the value inserted in the textbox is a
valid email suffix type. How do I check that

something like
 if ($(#element_id).val.className == emailSuffix)
 {
     ...
 }
 else
 {
     ...
 }