$(document).ready(function() {
  $("#submit").click(function(e) {
    e.preventDefault(); // don't let browser submit
    var name = $('#name').val();
    var age  = $('#age' ).val();
    if( name && age ){
      $.get(url,
          { name: name, age: age },
          function(data){
            $('#somediv').html(data); // replace div contents with new data
          });
    } else {
      alert('Missing form fields!);
    }
  });
});