PAC File iRule - advanced strings

could you make cleared what you exactly want, i dont understand the "if reponse is succesful"

in principle the proxy pac does part of what you want, you can say for dns zone x.com use proxy A and for dns zone y.com use proxy B. the example is in the page you have shown.

if you want to deliver different proxy pac files for different requests that might be more tricky. i believe (but please double check) you only request the proxy pac once when you start the browser. if you do another request it wont request another proxy pac file.

anyway please explain with more detail what you request is.