Invalid Text for a Document print event

I have been trying to find an answer to this for a couple days now any help would be much appreciated.

Here is what I am trying to accomplish.

     I have a document that I would like to be completely filled out before our data entry inputs that data from the fields.

     I know with a print event there is no way to prevent the user from printing, so what I would like is to have the document print INVALID in big text across the form so date entry does not waste too much time

     Also I would like for a message to pop up that alerts the user they did not fill out the form in its entireity.

I am pretty new to Java script but I think if anyone could point me in he write direction I could figure it out.

Thanks again