How to pass java variable in javascript

I am trying to create a min date and max date validation form in HTML and javascript. I have some issue about how to solve this problem.

my java code

 String sql = "select * from date";
    Class.forName("com.mysql.jdbc.Driver");
    Connection con = DriverManager.getConnection("jdbc:mysql://localhost:3306/Test","root","");
    PreparedStatement pre = con.prepareStatement(sql);
    ResultSet Re = pre.executeQuery();
    if(Re.next())
    {

        String msdfdate = Re.getString("sdate");
        JOptionPane.showMessageDialog(null, msdfdate);
}
}catch(Exception e)
{
    JOptionPane.showMessageDialog(null, e);
}

my javascript code

var kkr = <%=msdfdate%>;
       alert(kkr);
var today = new Date();
var dd = today.getDate();
var mm = today.getMonth()+1; //January is 0!
var yyyy = today.getFullYear();
 if(dd<10){
        dd='0'+dd
    } 
    if(mm<10){
        mm='0'+mm
    } 

today = yyyy+'-'+mm+'-'+dd;
startdate = dates;
document.getElementById("datefield").setAttribute("min", startdate)
document.getElementById("datefield").setAttribute("max", today);

How to solve this pass java DB variable to the javascript.