Preview button to show PDF without submitting post data?

PHP Users, I have a page that generates a PDF document using PHP. It takes form data filled in by the user to fill out the PDF When the user clicks "submit", it emails that PDF document to the intended recipient. However, I would like to add a "preview" function as well. But for a variety of reasons, instead of submitting the form data through post and re-filling all the fields with the selected data, I'd like to be able to open a new window with an example PDF without actually submitting the form. I think this might need JavaScript, but I'm not sure. Is this possible? Thank you for any advice. -- Dave M G