This is a similar questin asked here about signing a text or document with javascript on client side using a private key from the browser keystore, but this is really old question and the most voted answer is almost 6 years old. As far as I can't reply a comment because my reputation, I take the liberty to ask that again.
I didn't found much documentation about using the keystores from browser to sing data, but I find a very interesting topic to use this certificates to validate and authenticate user comunications when validating forms or uploading documents.
I allways try to find the answer searching before asking, but I'm dissapointed about not finding anything that eases that process.
At last, is there any way to use the client certificate from brower keystore with javascript to sign text?
Thanks