javascript - Receiving NULL in parameter when passing from js to Servlet. -

i getting null when trying receive parameter javascript. have gone through few post, not figure out making mistake in code.

below code sending request:

function funconchange() {     var index = document.detail.class.selectedindex;     var valueselected = document.detail.class.options[index].value;      handlerequeststatechange = function()     {         // check see if state change "request complete", ,         // there no server error (404 not found, 500 server error, etc)         if (xmlhttp.readystate==4 && xmlhttp.status==200)          {             var substring=xmlhttp.responsetext;             alert("alert dialog! gaurav");         }     }     var xhr = new xmlhttprequest();     xhr.open('post', 'http://localhost:8080/reportfetcher/formhandler', true);     xhr.send(valueselected); } 

i getting valueselected following piece of code , valueselected's correct:

<select name="class" onchange="funconchange()">             <option value="none">none</option>             <option value="first">first</option>             <option value="second">second</option>             <option value="third">third</option>             <option value="fourth">fourth</option>             <option value="fifth">fifth</option>             <option value="sixth">sixth</option>             <option value="seventh">seventh</option>             <option value="eighth">eighth</option>             <option value="ninth">ninth</option>             <option value="tenth">tenth</option>         </select><br> 

i receiving callback on onpost() of formhandler.java

protected void dopost(httpservletrequest request,         httpservletresponse response) throws servletexception, ioexception {     log.info("in form dopost");     string selectedclass = request.getparameter("class");     log.info(selectedclass);  } 

problem: selectedclass null here.

suggest making mistake.

try

function funconchange() {     var index = document.detail.class.selectedindex;     var valueselected = "class="+document.detail.class.options[index].text;      .....     .....      xhr.send(valueselected); }