Can you send data from Java variables into JavaScript

?

no

But you can write the Javascript with the data embedded.
[ April 07, 2005: Message edited by: Bear Bibeault ]

You can have Java variables passing values into Javascript but not other way round.

Are you talking about the server side, writing Javascript from inside a JSP or the client side where Javascript actually executes?
If you mean the server side - I suggest that you start with a mock-up plain HTML page containing Javascript that does what you want, then figure out how to get JSP to write that HTML.
Bill

You can have Java variables passing values into Javascript but not other way round.

No, you can't. They cannot inter-operate in any fashion. But as I stated, Java can be used to generate the Javascript that will eventually be sent to the client. That is not at all the same as "passing Java variables into Javascipt".

As it is about "you can". Yes you can.

script> var frequency = <%=frequency%>; var startTime = <%=startTime%>; function getMessages(){ alert(frequency); alert(startTime); } </script>

But you must view that resultant html file. As JSP is server-side technology and javascript is, on the other hand, client-side.

Yes, that is generating Javascript to be sent to the client. There is no "passing" in the Java sense of the term involved.