Javascript and PHP to generate "live" print preview

I want to be able to enter data and use Javascript onChange/onBlur/etc to render a "live" print preview; with page breaks. The ultimate goal is to have a PDF file that can be saved/emailed/etc that will be identical to the "preview". The data is to be stored in a MySQL database, I'm figuring AJAX to write it while entry.

Has anyone heard of a library (ideally free; purchase is an option) that can do this? If not, can you 开发者_如何学编程point me towards what can help me write something?

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There are tons of PDF creation libraries for the PHP, you can easily google it.
http://www.fpdf.org/ for example