I recently experienced a problem with a new pac file with chrome, (same pac file with IE and Firefox works).

I supposed that my problem is due to myIpAddress() function, see this post, which do not return my main ip address.

I would like to make some tests to debug pac file, but according to this post, debug function is no longer supported.

I also tried to use some options from this post.

In the chrome://net-internals/#proxy tab, I see which pac file is used, but nothing more.

And with the chrome://net-internals/#events tab, I see each request, but when I filter events with PROXY_SCRIPT_DECIDER, it returns no events.

I think my problem is related to myIpAddress, so how to test myIpAddress function, and is there a way to debug pac file without alert() ?


I didn't find the information anywhere, but chrome shows alert in chrome://net-internals/#events tab with description : PAC_JAVASCRIPT_ALERT.

Also you can find what chrome use as proxy in tab : chrome://net-internals/#proxy

  • 3
    Unfortunately this is no longer that easy (at least in Chrome Version 71.0.3578.98)
    – jan-glx
    Jan 29 '19 at 9:44
  • How to debug, now that net-internals/#events is removed?
    – Tino
    Sep 6 '20 at 10:08

As of 2020, I'd do it with:


and it's companion netlog-viewer to browse the information.


You can try out https://github.com/MamoruAsagami/PacTestBench. You need Java runtime environment in to run it, however.

  • It requires -myIpAddress as a parameter, so it can't be used for debugging that feature. Plus, it only seems to be able to test whether the right proxy string is returned. That's less helpful than logging internal variable values.
    – Quantum7
    Jan 10 '19 at 14:10

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.