function ajaxPost(url, postData, callback, action) {
         var req;
         try {
                 req = window.XMLHttpRequest ? new XMLHttpRequest(): new ActiveXObject("Microsoft.XMLHTTP");
             } catch (e) {
                 req = null;

                 if (req == null)
                      alert("Error creating request object!");
        }
        req.onreadystatechange = function() {
                if (req.readyState == 4 && req.status == 200) {
                         if(action == 'loeschen'){
                         for(var i=0; i<document.getElementById('tabelle').elements.length; i++) {
                                 var el = tabelle.elements[i];
                                 var type = (el.type || '');
                                 if(type.match(/^(checkbox)$/i) && el.checked) {
                                  document.getElementById('spalte'+el.value).style.display = 'none';
                                 }
                        }
                     }
             }
        }

        req.open('POST', url+'?myaction='+action, true);
        req.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded');
        req.send(postData);

        return false;
}

function getFormData(form, asArray) {
        var ret;
        var add = function(n, v) {
                if(asArray) {
                        if(ret == null) ret = new Array();
                        ret[n] = escape(v);
                } else {
                        ret = (ret == null ? '' : ret+'&') + n +'='+ escape(v);
                }
        };

        for(var i=0; i<form.elements.length; i++) {
                var el = form.elements[i];
                var type = (el.type || '');

                if(type.match(/^(text|hidden|textarea)$/i) || (type.match(/^(radio|checkbox)$/i) && el.checked)) {
                        add(el.name, el.value);
                } else if(el.nodeName.match(/^select$/i)) {
                        for(var j=0; j<el.options.length; j++) {
                                if(el.options[j].selected) {
                                        add(el.name, el.options[j].value);
                                }
                        }
                } else if(el.nodeName.match(/^textarea$/i)) {
                        add(el.name, el.value);
                }
        }
        return ret != null ? ret : (asArray ? new Array() : '');
}