How to do the password managers auto fill username, password in form?

Question

I want to make a password manager (Vault) which stores username, password and website. When the user of my Vault click on particular site through my web-application I want to redirect and auto-fill this username and password. On the clicked site.

I am have made databases and stuff. But how do I auto-populate the form. If I don't know the id or name of text box?

If there are some api's or ML algos which can parse and tell me id's for text and password. I thank you in adv. Also if someone knows how google knows which field to fill with what, I am available to hear that as well.

Answer 1

https://github.com/bitwarden/browser/blob/38e4ba087930e491628435201b4796fb4bfe8463/src/services/autofill.service.ts#L188

Finally found this. They basically hard code and search for them in html page. Well this was interesting don't you think.