proxy.pac file performance optimization
Solution 1:
If you are just checking for equality use '==' for comparison. The shExpMatch function allows for shell expressions (* and ? in their DOS shell meanings) so the second argument has to be parsed. The script runs in the browser, once (or less) per request so performance is not an issue but it makes the code clearer if you write what yuo mean.
I would also use a variable to hold the proxy expression. It probably won't save run-time storage as the repeated literal is probably re-used, but it will make the code easier to read.