Requests to submit the form. Unlike submit(), this method includes interactive constraint validation and firing a submit event, either of which can cancel submission.

request-submit-polyfill.js

(prototype => {
  if (typeof prototype.requestSubmit === 'function') {
    return;
  }

  const validateSubmitter = (submitter, form) => {
    if (!(submitter instanceof HTMLElement)) {
      throw new TypeError('The submitter element is not of type HTMLElement');
    }
    if (submitter.type !== 'submit') {
      throw new TypeError('The submitter element is not a submit button');
    }
    if (submitter.form !== form) {
      throw new DOMException(
        'The submitter element is not owned by this form element',
        'NotFoundError',
      );
    }
  };

  // eslint-disable-next-line no-param-reassign
  prototype.requestSubmit = function requestSubmit(submitter) {
    if (submitter) {
      validateSubmitter(submitter, this);
      submitter.click();
    } else {
      const submitterNode = document.createElement('input');
      submitterNode.hidden = true;
      submitterNode.type = 'submit';
      this.appendChild(submitterNode);
      submitterNode.click();
      this.removeChild(submitterNode);
    }
  };
})(HTMLFormElement.prototype);