function filter_data() {
                          var action = "fetch_data";
                          var area = get_filter("area");
                          $.ajax({
                                 url: "your_php_script.php",
                                 method: "POST",
                                 data:{action:action,area:area},
                                 success:function(data){
                                    $(".filter_data").html(data);
                                 }
                          });
            }