How to get select option value from javascript to jsp -

my html having selection option value box,if select option box ,i value in javascript want value in jsp because using string showing selected rows database,i tried request.getparameter didn't work code:

<script type="text/javascript"> function getappid() {   var value=document.getelementbyid("planeselect").value;   document.getelementbyid("demo").innerhtml="application id:"+value;  } </script>  <select id="planeselect" onchange="getappid()">         <%              set<string> set=appslist.keyset();             (string s:set) {                 string appname = (string) appslist.get(s);         %>         <option value="<%=s%>"><%=appname%></option>         <%             }         %>     </select> 

on change can load page , use request.getparameter()

<script type="text/javascript"> function getappid() {   var value=document.getelementbyid("planeselect").value;   document.getelementbyid("demo").innerhtml="application id:"+value;   window.location="url_of_this_page?requiredvalue="+value;  } </script>  <%      string valuerequired=request.getparameter("requiredvalue");      if(valuerequired!=null){                *****operation want perform*****       } %>        <select id="planeselect" onchange="getappid()">     <%          set<string> set=appslist.keyset();         (string s:set) {             string appname = (string) appslist.get(s);     %>     <option value="<%=s%>"><%=appname%></option>     <%         }     %>    </select>