<script>
$('#myform').on('submit', function(e){
  let username = $("#username").val();
  let password = $("#password").val();
  let url = $('#myform').attr('action');
  $.post(url, {
    username:username,
    password:password
  }, function(d){
    alert('success');
  });
});
$('#login').click(function(e){
  e.preventDefault();
  $('#myform').submit();
});