How to find critical rules on a page that requires authorization

[mdvorscak]

Currently when I follow the example in the README

var request = require('request');
var path = require( 'path' );
var criticalcss = require("criticalcss");
var fs = require('fs');
var tmpDir = require('os').tmpdir();

var cssUrl = 'myCSSURL';
var cssPath = path.join( tmpDir, 'style.css' );
request(cssUrl).pipe(fs.createWriteStream(cssPath)).on('close', function() {
  criticalcss.getRules(cssPath, function(err, output) {
    if (err) {
      throw new Error(err);
    } else {
      const rules = JSON.parse(output);
      criticalcss.findCritical("myPageThatRequiresAuth", { rules:  rules}, function(err, output) {
        if (err) {
          throw new Error(err);
        } else {
          console.log(output);
        }
      });
    }
  });
});

It will only match rules that are on my login page. Is there a way to pass credentials?