Read From A Textfile?

I have a database with information of my users, lets say their date of
birth.

I want them to be able to go to my site, and login with a username and
password, after which they get to see what their date of birth is (according
to what's stored in the database).

I want to upload a textfile named "userinfo.txt" structured like:
<username>;<password>;<date of birth>, for example:
"johndoe";"johnpass";"1985-11-25"
"marydoe";"marypass";"1986-02-12"


What's the javascript to have a "username/password" box popup, and when a
valid name/pass was entered show the appropriate date of birth?