This method is a shortcut for .on( "submit", handler ) in the first variation, and .trigger( "submit" ) in the third.
The submit event is sent to an element when the user is attempting to submit a form. It can only be attached to <form> elements. Forms can be submitted either by clicking an explicit <input type="submit">, <input type="image">, or <button type="submit">, or by pressing Enter when certain form elements have focus.