/*1.*/function replaceText(el, text) {
/*2.*/  if (el != null) {
/*3.*/    clearText(el);
/*4.*/    var newNode = document.createTextNode(text);
/*5.*/    el.appendChild(newNode);
  }
}

function clearText(el) {
  if (el != null) {
    if (el.childNodes) {
      for (var i = 0; i < el.childNodes.length; i++) {
        var childNode = el.childNodes[i];
        el.removeChild(childNode);
      }
    }
  }
}

function getText(el) {
  var text = "";
  if (el != null) {
    if (el.childNodes) {
      for (var i = 0; i < el.childNodes.length; i++) {
        var childNode = el.childNodes[i];
        childNode.normalize();
        if (childNode.nodeType == Node.TEXT_NODE) {
          text = text + childNode.data;
        }
      }
    }
  }
  return text;
}

function pageRequest(id) {
  var pid = id;
  var url = 'server/pageLoader.php';
  
  request.open('POST', url, true);
  request.onreadystatechange = updatePage;
  request.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded');
  request.send('pid=' + escape(pid));
}

function updatePage() {
  if(request.readyState == 4) {
    if(request.status == 200) {
      alert(request.responseText);
      var jsonData = JSON.parse(request.responseText);
      
      var title = jsonData.title;
      var content = jsonData.content;
      var nav = jsonData.nav;
      
      var titleEl = document.getElementsByTagName('title')[0];
      var contentEl = document.getElementById('content_in');
      var navEl = document.getElementById('nav_in');
      // TUTAJ WYKORZYSTUJĘ FUNKCJE DO PODMIENIANIA ZAWARTOŚCI
      replaceText(titleEl, title);
      contentEl.innerHTML = content;
      navEl.innerHTML = nav;
      
    }
    else {
      var message = request.getResponseHeader("Status");
      if((message == null) || (message.length <= 0)) {
        alert('Błąd! Status żądania ma wartość '+request.status);
      }
      else {
        alert(message);
      }
    }
  }
}