$(document).ready(function(){
  $("#main_form").validate({
    errorPlacement: function(error, element) {}
   });
});

// Default implementation of section validation method:
// doesn't validate anything, just calls method submitForm with the given action.
function validateThisSection(formAction) {
  if (formAction.indexOf('submit') >= 0) {
    $('#send_application').val('yes');
  } else {
    $('#send_application').val('no');
  }

  return submitForm(formAction)
}

function submitForm(formAction) {
  var mainForm = $('#main_form');

  if (mainForm.valid()) {
    mainForm.get(0).action = formAction;
    mainForm.get(0).submit();
  }
  else {
    alert("Please populate all required fields (highlighted in red)");
  }
}