teste send POST js

#!/usr/bin/ruby
# test by Cooler_
# gems requeridas
require 'rubygems'
require 'selenium-webdriver'

# preparando webdriver, e o web browser a ser usado
driver = Selenium::WebDriver.for :firefox

# primeira URL para abrir no web browser
url = "http://192.168.0.127/dvwa/login.php"
driver.get url
# procura qual elemento vai apontar o cursor para escrita
#element=driver.find_element :name => "username"
# faz escrita no formulario
#element.send_keys "admin"
#element=driver.find_element :name => "password"
#element.send_keys "password"

script = '
var http = new XMLHttpRequest();
var url = "#{url}";
var params = "username=admin&password=password";
http.open("POST", url, true);

//Send the proper header information along with the request
http.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
http.setRequestHeader("Content-length", params.length);
http.setRequestHeader("Connection", "close");

http.onreadystatechange = function() {//Call a function when the state changes.
    if(http.readyState == 4 && http.status == 200) {
// soh aparece erro :-(
        alert(http.responseText);
    }
}
http.send(params);
 '
element = driver.execute_script script
sleep(100)

driver.quit