detect-button-form-attr-support.js

const sampleButton = document.createElement('button');
const sampleForm = document.createElement('form');
sampleForm.setAttribute('id', 'sample-form-for-polyfill');
sampleButton.setAttribute('form', 'sample-form-for-polyfill');

document.body.appendChild(sampleForm);
document.body.appendChild(sampleButton);

const isIE11 = !(window.ActiveXObject) && 'ActiveXObject' in window;
const supportsButtonFormAttr = (
  window.HTMLFormElement
  && sampleButton.form instanceof window.HTMLFormElement
  && !isIE11
);

document.body.removeChild(sampleForm);
document.body.removeChild(sampleButton);

console.log('Supports Button Form Attr', supportsButtonFormAttr);