Hubspot | Vanilla | Hubspot Form Callbacks

// https://legacydocs.hubspot.com/global-form-events
// onBeforeFormInit - onFormReady - onFormSubmit - onFormSubmitted
window.addEventListener('message', event => {
 if(event.data.type === 'hsFormCallback' && event.data.eventName === 'onFormReady') {
  // Form Ready
 } else if(event.data.type === 'hsFormCallback' && event.data.eventName === 'onFormSubmit') {
  // Form Submit
 }
});