function ShowAlert() {
  document.getElementById("alert").style.color="red";
  document.forms["frm"].className="form_links_invalid";
  alert("Alvorens u meer informatie kunt bekijken vragen wij u eenmalig uw gegevens aan de linker zijde in te vullen");
}

function validEmail(theEntry) {
  badEntry = false
  invalidChars = " /:,;"     
  if (theEntry == "") { 
    badEntry = true
  }
  for (i=0; i < 5; i++)  {
    badChar = invalidChars.charAt(i)
    if (theEntry.indexOf(badChar,0) > -1) {
      badEntry = true
    }
  }  
  atsignLoc = theEntry.indexOf("@",1)
  if (atsignLoc == -1) {
    badEntry = true
  }     
  if (theEntry.indexOf("@",atsignLoc+1) > -1) {
    badEntry = true
  }
  dotLoc = theEntry.indexOf(".",atsignLoc)
  if (dotLoc == -1) {
    badEntry = true
  }
  if (dotLoc+3 > theEntry.length) {
    badEntry = true
  }
  return badEntry
}

function ValidateForm(oForm) {
   var oFocusItem = null; var sMessage = new String;
   var bPassed = true; 
   var oItems = oForm.elements;
   for (var i = 0; i < oItems.length; i++) {
      if ( (oItems.item(i).className.indexOf('requiredfield') > -1) ) {
         if ( oItems.item(i).value.length < 1) { 
            oItems.item(i).className += ' invalidfield';
            if ( !oFocusItem ) oFocusItem = oItems.item(i);
            bPassed = false;
         } else if ( oItems.item(i).className.indexOf(' invalidfield') > -1) {
            oItems.item(i).className = 'requiredfield';
         }
      }
   }
   if (oForm.email){
      if (validEmail(oForm.email.value) == true) {
         oForm.email.className += ' invalidfield';
         if ( !oFocusItem ) oFocusItem = oForm.email;
         bPassed = false;
      }
   }
   if ( !bPassed && oFocusItem ) oFocusItem.focus();
   return bPassed;
}