(HTML) Download a PDF file instead of opening them in browser when clicked

With html5, it is possible now. Set a "download" attr in element.

<a href="http://link/to/file" download="FileName">Download it!</a>

Source : http://updates.html5rocks.com/2011/08/Downloading-resources-in-HTML5-a-download

This is only possible with setting a http response header by the server side code. Namely;

Content-Disposition: attachment; filename=fname.ext