The read-only submitter property found on the SubmitEvent interface specifies the submit button or other element that was invoked to cause the form to be submitted.

An element, indicating the element that sent the submit event to the form. While this is often an <input> element whose type is submit or a <button> element whose type is submit, it could be some other element which has initiated a submission process.

If the submission was not triggered by a button of some kind, the value of submitter is null.

See SubmitEvent for example code.