PKCS#11 in JavaScript

I’ve installed the PKCS#11 Module from “Nexus Personal Desktop” and I would like access to my SmartCard in a HSM via JavaScript. I found “https://developer.mozilla.org/en-US/docs/Mozilla/Add-ons/WebExtensions/API/pkcs11” where I can see the token and some information about the token. There it says " The pkcs11 API enables an extension to enumerate PKCS #11 security modules and to make them accessible to the browser as sources of keys and certificates."
How can I find the keys and certificates via JavaScript?