//http://www.admin-wissen.de/tutorials/eigene-tutorials/webentwicklung/ajax-tutorial/einfuehrung-in-ajax/
             function doIt(){

                 //erstellen des requests
                 var req = null;

                try{
                    req = new XMLHttpRequest();
                }
                catch (ms){
                    try{
                        req = new ActiveXObject("Msxml2.XMLHTTP");
                    }
                    catch (nonms){
                        try{
                            req = new ActiveXObject("Microsoft.XMLHTTP");
                        }
                        catch (failed){
                            req = null;
                        }
                    }
                }

                if (req == null)
                      alert("Error creating request object!");

                  req.open("GET", textdatei, true);

                //Beim abschliessen des request wird diese Funktion ausgeführt
                req.onreadystatechange = function(){
                    switch(req.readyState) {
                            case 4:
                            if(req.status!=200) {
                                alert("Fehler:"+req.status);
                            }else{
                                //schreibe die antwort in den div container mit der id content
                                document.getElementById('eins').innerHTML = req.responseText;
        }
                            break;

                            default:
                                return false;
                            break;
                        }
                    };

                  req.setRequestHeader("Content-Type",
                                      "application/x-www-form-urlencoded");
                req.send(null);
            }

document.write("<div id='eins'>")
document.write("<a href='#z' onclick='doIt();'>" + linktext + "<\/a>")
document.write("<\/div>")