Access session variable through javascript

<script language="javascript">
function getsession()
{

alert('<%=session("aaa")%>');
'<%session("aaa") = "bbb"%>' ;

var myvar = "Hey Buddy";
"<%session("aaa") = "'+ myvar +'" %>" ;this is not working through serverside access



alert('<%=session("aaa")%>');
alert('<%=session("aaa")%>');


 "<%=session("aaa")%>"="bbb";
alert('<%=session("aaa")%>');


}
</script>

<INPUT TYPE=SUBMIT onclick="return getsession();" VALUE="Upload!">