ajax send parameter to jsp but failed

I am trying to send data to my jsp via:"xhr.send(projectCode);" but apparently the parameter is not received when I am trying to realise it with System.out.print it is a null displayed. so the story from the begining. my javascript function send the parameter to the jsp whitch construct an xml file and resend to the first one. this will reconstruct my second dropdownList with th开发者_JS百科e xml code constructed and received. so the problem that the parameter dosent sent at all.

What should I do.

Just note in case the syntax whatever you have sent is like this:

url="postjob2.jsp?param=" + param;

After param=" keep a space and then the parameter. My issue got resolved as soon as I entered the space.

The simplest all-round solution is to run your application with a HTTP-tracer, such as fiddler for windows or wireshark. In that way you can see if the proper data is being submitted from your client to the server Given the amount of details you provide, I think this is the best starting point