/*This is the location of your PHP script*/
var url = "username.html?param=";

function updateName() {
  /* Print the message to use while checking the database: */
  document.getElementById('checked').innerHTML = "Sprawdzam...";
  /* We're assuming your username input ID is "username" */
  var name = document.getElementById("username").value;
  http.open("GET", url + escape(name), true);
  http.onreadystatechange = handleHttpResponse;
  http.send(null);
}

function handleHttpResponse() {
  if (http.readyState == 4) {
    results = http.responseText;
    /* Again, we're assuming your username input ID is "username" */
    var name = document.getElementById("username").value;
    /* If the username is available, Print this message: */
    if(results == "") results = "<font color=\"green\">Login <i>"+name+"</i>  jest dostêpny!</font>";
    document.getElementById('checked').innerHTML = results;
  }
}

function getHTTPObject() {
  var xmlhttp;
  if (!xmlhttp && typeof XMLHttpRequest != 'undefined') {
    try {
      xmlhttp = new XMLHttpRequest();
    } catch (e) {
      xmlhttp = false;
    }
  }
  return xmlhttp;
}
var http = getHTTPObject();