How to make a digital signature in a web application (JavaScript) using a smartcard?

After some more googling I found the answer. Mozilla export part of its NSS module via window.crypto object. A more standard way of doing such operation is probably via DOMCrypt, that is currently discusses in W3C. Google Chrome developer will wait W3C to standardize DOMCrypt, while Microsoft require the use of an ActiveX object as explained here (this works even with Firefox/Chrome/Opera on Windows).

Currently (may 2016) it is not possible.

Chrome has dropped Java support. 'Windows edge' will not have. IE11 support is bad, and Oracle has decided to discontinue the java plugin. It would only be possible with Firefox, older versions of IE and the Java plugin.

The new WebCryptographyApi standard provides digital signature support for browsers, but it does not have pcks#11 support

Real e-goverment solution to solve this: 1) Install a local Java application on the user's PC. The application listens on a port as, for example 5678 2) In your page, javascript detects whether there is support for applets 3) If there is no support, connects to the application in the form http://127.0.01:5678/sign and sends the data to sign. 4) The application is local and has no trouble using the operating system keystore, which includes drivers PKCS # 11. Make digital signature and prepares the result 5) page javascript periodically query the result and retrieves it when ready