function createRequestObject() {
  try {
  	xmlhttp = window.XMLHttpRequest ? new XMLHttpRequest() : new ActiveXObject("Microsoft.XMLHTTP");
  } catch(e) {
    alert('Erreur, votre navigateur n\'est pas compatible.');
  }
  return xmlhttp;
}

var http = createRequestObject();
var sess = createRequestObject();

function refreshimg() {
  var url = 'pages/captcha/image_req.php';
  dorefresh(url, displayimg);
}

function dorefresh(url, callback) {
  sess.open('POST', 'pages/captcha/newsession.php', true);
  sess.send(null);
  http.open('POST', url, true);
  http.onreadystatechange = displayimg;
  http.send(null);
}

function displayimg() {
  if(http.readyState == 4) {
    var showimage = http.responseText;
    document.getElementById('captchaimage').innerHTML = showimage;
  }
}

function check() {
  var submission = document.getElementById('captcha').value;
  var url = 'pages/captcha/process.php?captcha=' + submission;
  docheck(url, displaycheck);
}

function docheck(url, callback) {
  http.open('GET', url, true);
  http.onreadystatechange = displaycheck;
  http.send(null);
}

function displaycheck() {
  if(http.readyState == 4) {
    var showcheck = http.responseText;
    if(showcheck == '1') {
      document.getElementById('captcha').style.border = '1px solid #49c24f';
      document.getElementById('captcha').style.background = '#bcffbf';
    }
    if(showcheck == '0') {
      document.getElementById('captcha').style.border = '1px solid #c24949';
      document.getElementById('captcha').style.background = '#ffbcbc';
    }
  }
}