submit event does not fire if submit initiated programmatically

That's because you shouldn't just use the submit function, but trigger the submit like:

$("#MyForm").trigger('submit');

Browsers don't fire the form's onsubmit handler when you manually call form.submit().

jQuery also mimicks used to mimick that (see this "wontfix" "bug" report).

See also:

• Should jQuery's $(form).submit(); not trigger onSubmit within the form tag?
• JQuery: on submit doesn't work