如何在javascript函数内部传递java变量？

Question

javascript code:

<script type="text/javascript">

function submitform(){
    //  alert("inside submit");
    <% String username1=(String)session.getAttribute("UserName");

    if(username1 == null || username1.equals("undefined")){%>
        alert("please login to submit");
    <% }else{ %>
        //alert("In Submit form");

        var frm=document.getElementById("myForm");
        frm.action="Electionservlet?formidentity=editYPName&Username="+<%=username1%>;
        //alert("before submit");
        frm.submit(); 

    <%}%>
}

</script>

when i click on the submit button the abobe function('submitform') is called. so what i want here is how can i pass a java variable(username1) through javascript function and get that value inside my servlet???

Answer 1

As <%=username1%> is not a javascript variable so you cant use + like that

frm.action="Electionservlet?formidentity=editYPName&Username=<%=username1%>";

                                                              ^--------// removed +

Answer 2

You can simply use Expression Language in jsp to assign your attribute to a js variable and avoid the scriptlets. It will make your code more readable.

function submitform(){
    //  alert("inside submit");
    var username1=${sessionScope.UserName};

    if( username1 == null || username1 == "undefined" ){
        alert("please login to submit");
    }else{
        //alert("In Submit form");
        var frm=document.getElementById("myForm");
        frm.action="Electionservlet?formidentity=editYPName&Username="+username1;
        //alert("before submit");
        frm.submit(); 

    }
}