Is there a way to connect a card reader to my web application (javascript) so that the user don't have to manually type in the credit card information?
This web app is for buying products on a store. The user clicks on what items he want to purchase and then he swipes the credit card in the reader and he will get a receipt.
Actually, it is possible due to the fact that simple USB card readers act as keyboard input devices. Since it acts as a keyboard input, once an inputbox is in focus you could swipe the card, push it to a hidden field using some nifty jQuery etc and then process it from there.
Please see my answer on that question that Maris linked to.
EDIT: 2/2016
I created a GitHub Gist with a very simple jQuery implementation.