On site example.com I have 3 different accounts (e.g. usernameA:passwordA, usernameB:passwordB, usernameC:passwordC). I have let the browsers store them.
So the next time I go to example.com, the browser autofill/prefills the username and password fields of the first account (usernameA:passwordA). There's a dropdown list containing the other accounts (usernameB:passwordB and usernameC:passwordC.)
When the first usernameA:passwordA is autofill/prefilled by browser... is it known to example.com before I choose usernameC:passwordC? (if example.com is tracking form input fields?)
Can example.com know that both usernameA and usernameC are used by same person? (by tracking form input fields?)
Can example.com know that the browser had autofill/prefilled the form fields of currently logged-in user (which is usernameC) with usernameA & passwordA first, before this user manually chose usernameC?
So it appears my question remains without any interest. Meanwhile I have tried googling this issue, and tried Chrome, Firefox and Opera forums, but haven't found anything (most probably because I am not using right terms to look for perhaps?). I'll just leave it here hoping someone in the know eventually stumbles on to it. Thanks.
It appears that Browsers do not sent the <input> fields of login and passwords to the sites until after submission via <form> so I think it's a safe practise.