function checkform() {
  for (i=0;i<fieldstocheck.length;i++) {
    if (eval("document.subscribeform.elements['"+fieldstocheck[i]+"'].type") == "checkbox") {
      if (document.subscribeform.elements[fieldstocheck[i]].checked) {
      } else {
        alert("Vul het volgende in "+fieldnames[i]);
        eval("document.subscribeform.elements['"+fieldstocheck[i]+"'].focus()");
        return false;
      }
    }
    else {
      if (eval("document.subscribeform.elements['"+fieldstocheck[i]+"'].value") == "") {
        alert("Vul het volgende in "+fieldnames[i]);
        eval("document.subscribeform.elements['"+fieldstocheck[i]+"'].focus()");
        return false;
      }
    }
  }
  for (i=0;i<groupstocheck.length;i++) {
    if (!checkGroup(groupstocheck[i],groupnames[i])) {
      return false;
    }
  }
  
  return true;
}

var fieldstocheck = new Array();
var fieldnames = new Array();
function addFieldToCheck(value,name) {
  fieldstocheck[fieldstocheck.length] = value;
  fieldnames[fieldnames.length] = name;
}
var groupstocheck = new Array();
var groupnames = new Array();
function addGroupToCheck(value,name) {
  groupstocheck[groupstocheck.length] = value;
  groupnames[groupnames.length] = name;
}

function compareEmail()
{
  return (document.subscribeform.elements["email"].value == document.subscribeform.elements["emailconfirm"].value);
}
function checkGroup(name,value) {
  option = -1;
  for (i=0;i<document.subscribeform.elements[name].length;i++) {
    if (document.subscribeform.elements[name][i].checked) {
      option = i;
    }
  }
  if (option == -1) {
    alert ("Vul het volgende in "+value);
    return false;
  }
  return true;
}

function toggleLayer( whichLayer ){
	var elem, vis;  if( document.getElementById ) // this is the way the standards work    
	elem = document.getElementById( whichLayer );  else if( document.all ) // this is the way old msie versions work     
	elem = document.all[whichLayer];  else if( document.layers ) // this is the way nn4 works    
	elem = document.layers[whichLayer];  vis = elem.style;  // if the style.display value is blank we try to figure it out here  
	if(vis.display==''&&elem.offsetWidth!=undefined&&elem.offsetHeight!=undefined)    
	vis.display = (elem.offsetWidth!=0&&elem.offsetHeight!=0)?'block':'none';  
	vis.display = (vis.display==''||vis.display=='block')?'none':'block'; }