Seems like Paypal response is also in form of POST/NVP formatted query string:
Code:
Interpret the Response
PayPal processes your request and posts back a reponse in NVP format. Add code to your web
application to do the following tasks:
1. Receive the HTTP post response, and extract the NVP string.
2. URL-decode the parameter values as described in “URL-Encoding” on page 14.
3. Take appropriate action for successful and failed reponses.
So my javascript function above "handleResponse" should basically parse response query string? How did they do it without AJAX?