function GetXmlHttpObject(){
        var xmlhttp = null;
        if(window.XMLHttpRequest){
        xmlhttp = new XMLHttpRequest();
        }else{
            try{
                xmlhttp = new ActiveXObject("Microsoft.XMLHTTP");
            }catch(e){
                window.alert("Uw browser ondersteunt het XMLHttpRequest object niet!");
            }
        }
        
        return xmlhttp;
    } 

function stateChanged() 
{ 
   if (xmlHttp.readyState==4)
   {
      if(xmlHttp.status == 200)
      { 
         document.getElementById("content").innerHTML=xmlHttp.responseText ;
      } 
	  else
	  {
	  	alert("Probleem met het request!");
	  }
   }
}
function showVragen(str)
{
	xmlHttp=GetXmlHttpObject();
	if (xmlHttp==null)
	{
      alert ("Browser does not support HTTP Request")
      return
    }
    var url="getcontent.php";
    url=url+"?boek="+str;
    url=url+"&sid="+Math.random();
    xmlHttp.onreadystatechange=stateChanged;
    xmlHttp.open("GET",url,true);
    xmlHttp.send(null);
}
function getCount()
{
	xmlHttp=GetXmlHttpObject();
	if (xmlHttp==null)
	{
      alert ("Browser does not support HTTP Request")
      return
    }
    var url="countvragen.php";
    url=url+"?sid="+Math.random();
    xmlHttp.onreadystatechange=countChanged;
    xmlHttp.open("GET",url,true);
    xmlHttp.send(null);
}

function countChanged() 
{ 
   if (xmlHttp.readyState==4)
   {
      if(xmlHttp.status == 200)
      { 
         document.getElementById("total").innerHTML=xmlHttp.responseText ;
      } 
	  else
	  {
	  	alert("Probleem met het request!");
	  }
   }
}

function insertAtCursor(myField, myValue) {
	//IE support
	if (document.selection) {
		myField.focus();
		sel = document.selection.createRange();
		sel.text = myValue;
	}
	//MOZILLA/NETSCAPE support
	else if (myField.selectionStart || myField.selectionStart == '0') {
		var startPos = myField.selectionStart;
		var endPos = myField.selectionEnd;
		myField.value = myField.value.substring(0, startPos)
		+ myValue
		+ myField.value.substring(endPos, myField.value.length);
}	 
	else {
	myField.value += myValue;
	}
}

   var http_request = false;
   function makePOSTRequest(url, parameters) {
      http_request = false;
      if (window.XMLHttpRequest) { // Mozilla, Safari,...
         http_request = new XMLHttpRequest();
         if (http_request.overrideMimeType) {
         	// set type accordingly to anticipated content type
            //http_request.overrideMimeType('text/xml');
            http_request.overrideMimeType('text/html');
         }
      } else if (window.ActiveXObject) { // IE
         try {
            http_request = new ActiveXObject("Msxml2.XMLHTTP");
         } catch (e) {
            try {
               http_request = new ActiveXObject("Microsoft.XMLHTTP");
            } catch (e) {}
         }
      }
      if (!http_request) {
         alert('Cannot create XMLHTTP instance');
         return false;
      }
      
      http_request.onreadystatechange = alertContents;
      http_request.open('POST', url, true);
      http_request.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
      http_request.setRequestHeader("Content-length", parameters.length);
      http_request.setRequestHeader("Connection", "close");
      http_request.send(parameters);
   }

   	function alertContents() {
      if (http_request.readyState == 4) {
         if (http_request.status == 200) {
            //alert(http_request.responseText);
            result = http_request.responseText;
            document.getElementById('respond').innerHTML = result;            
         } else {
            alert('There was a problem with the request.');
         }
      }
   }
   
   	function get(obj) {
      var poststr = "vraag=" + encodeURI( document.getElementById("vraag").value ) +
                    "&antwoord=" + encodeURI( document.getElementById("antwoord").value ) +
                    "&boek=" + encodeURI ( document.getElementById("boek").value ) +
                    "&hoofdstuk=" + encodeURI ( document.getElementById("hoofdstuk").value ) +
                    "&vers=" + encodeURI ( document.getElementById("vers").value );
      makePOSTRequest('post.php', poststr);
      document.form.vraag.value="";
      document.form.antwoord.value="";
   	}
  	function startLoad(){
   		document.getElementById('respond').innerHTML = "<img src=loading.gif height=11px width=220px />";
   	}
   	
function chaptersChanged() 
{ 
   if (xmlHttp.readyState==4)
   {
      if(xmlHttp.status == 200)
      { 
         document.getElementById("hoofdstuk-div").innerHTML=xmlHttp.responseText ;
      } 
	  else
	  {
	  	alert("Probleem met het request!");
	  }
   }
}
function changeChapters(boek)
{
	xmlHttp=GetXmlHttpObject();
	if (xmlHttp==null)
	{
      alert ("Browser does not support HTTP Request")
      return
    }
    var url="getchapters.php";
    url=url+"?id="+boek;
    url=url+"&sid="+Math.random();
    xmlHttp.onreadystatechange=chaptersChanged;
    xmlHttp.open("GET",url,true);
    xmlHttp.send(null);
}