Example 2: Proxy Local Servers Outside the Firewall

This example resembles Example 1: Proxy All Servers Except Local Hosts, but it uses the proxy for local servers that are outside the firewall. If hosts such as the main web server belong to the local domain but are outside the firewall and are only reachable through the proxy server, those exceptions are handled using the localHostOrDomainIs()() function:

    function FindProxyForURL(url, host)
    {
        if ((isPlainhost name(host) ||
        dnsDomainIs(host, ".example.com")) &&
        !localHostOrDomainIs(host, "www.example.com") &&
        !localHostOrDoaminIs(host, "merchant.example.com"))
            return "DIRECT";
        else
            return "PROXY w3proxy.example.com:8080; DIRECT";
    }

This example uses the proxy for all hosts except local hosts in the example.com domain. The hosts www.example.com and merchant.example.com also go through the proxy.

The order of the exceptions increases efficiency: localHostOrDomainIs()() functions get executed only for URLs that are in the local domain, not for every URL. In particular, notice the parentheses around the or expression before the and expression.