//<script>
        var checkFields = [];

        // Alle velden opgeven
        //addCheckField( veldnaam , HtmlName , type )
        // Voor type kun je kiezen "radio" (radio box)
        // "email" (checkt email adres)
        // "tel" (checkt telefoon nummer adres)
        // /RegExp/ voor aangepaste check
        // leeg laten om te checken of er "iets" is ingevuld - werkt
        // voor textbox, checkbox, textarea en select

        //addCheckField("Radiobutton","sRadiobutton","radio");
        addCheckField("Uw naam","realname");
        addCheckField("Uw e-mailadres","email","email");
        addCheckField("Uw telefoonnummer","Telefoon","tel");
        addCheckField("Uw vraag","Vraag");

        var bSubmit = false;
        function addCheckField (title,name,type,opt) {
          checkFields[checkFields.length] = [title,name,type,opt];
          }
        function checkForm (form) {
          if (bSubmit) {
            alert('U heeft al op verzenden gedrukt, een moment geduld a.u.b.');
            return false;
            }
          var sError = "";
          for (var i = 0; i < checkFields.length; i++) {
            if (checkFields[i][2] == "radio") {
              var ok = false;
              for (var b = 0; b < form[checkFields[i][1]].length; b++) {
                if (form[checkFields[i][1]][b].checked) ok = true;
                }
              if (!ok) sError += checkFields[i][0] + "\n";
              }
            else if (checkFields[i][2] == "tel") {
              var value = sTrim(form[checkFields[i][1]].value);
              value = value.replace(/\D/g,'');
              if (value.length != 10) sError += checkFields[i][0] + "\n";
              }
            else if (checkFields[i][2] == "email") {
              var value = sTrim(form[checkFields[i][1]].value);
              if (!/^.+@.+\...+$/.test(value)) {
                if (value == "" && checkFields[i][3]) { ; }
                else { sError += checkFields[i][0] + "\n"; }
                }
              }
            else if (checkFields[i][2]) {
              var value = sTrim(form[checkFields[i][1]].value);
              if (!checkFields[i][2].test(value)) sError += checkFields[i][0] + "\n";
              }
            else {
              var value = sTrim(form[checkFields[i][1]].value);
              if (value.length == 0) sError += checkFields[i][0] + "\n";
              }
            }
          if (sError!='') {
            alert("De volgende velden zijn niet of niet juist ingevuld: \n"+sError);
            bSubmit = false;
            }
          else {
            bSubmit = true;
            }
          return bSubmit;
          }

        function sTrim(sSource)
        {
            var oBegin=new RegExp("^[ ]+","g");
            var oEnd=new RegExp("[ ]+\$","g");
            var sReturn=sSource.replace(oBegin,'');
            return sReturn.replace(oEnd,'');
        }