PAC

function FindProxyForURL(url, host) {

  var proxyserver = 'PROXY:PORT';

  var proxylist = new Array(

    "*userapi.*",

    "*vk.*",

  );

  for(var i=0; i<proxylist.length; i++) {

    var value = proxylist[i];

    if ( shExpMatch(host, value) ) {

      return "PROXY "+proxyserver;

    }

  }

  return "DIRECT";

}