The SubmitEvent() constructor creates and returns a new SubmitEvent object, which is used to represent a submit event fired at an HTML form.

type

A string with the name of the event. It is case-sensitive and browsers always set it to submit.

options Optional

An object that, in addition of the properties defined in Event(), can have the following properties:

submitter Optional

An HTMLElement object that is the submit button that triggered the form submission.

A SubmitEvent object configured using the given inputs.

This code snippet locates a form in the current document, and then an HTML <button> within the form with the class submit on it. Next, a new SubmitEvent is created, configured with its submitter set to the identified button (or null if the button wasn't found). Then the event is sent to the form, telling the form that it's been submitted by the button.

const form = document.querySelector("form");
const formTrigger = form.querySelector("button.submit");
const submitEvent = new SubmitEvent("submit", { submitter: formTrigger });

form.dispatchEvent(submitEvent);

This is a somewhat contrived example, as you can do nearly all of this much more easily, but this gives you deep control over the process that can be useful.