Events

The form emits ordinary CustomEvents that bubble, so every framework can bind them natively and no wrapper package is required.

Event	When	detail
fb:ready	The form has rendered	{ form }
fb:step	The visitor moved between steps	{ index, total, direction }
fb:submit	A submission is being sent	{ data }
fb:success	It was accepted	{ submission }
fb:redirect	The form is about to navigate	{ url }
fb:close	An overlay was dismissed	none

document.addEventListener('fb:success', (event) => {
    // e.g. a conversion event
    window.dataLayer?.push({ event: 'form_submitted' });
});

Because they bubble, a listener on document catches every form on the page. Listen on a wrapper element instead when you have several and need to tell them apart.

Inside an iframe

In iframe mode the events cross a frame boundary as postMessage, and the loader re-emits them on your container. The parent only accepts a message when the source window, the origin and the instance id all match: checking the origin alone is not enough, because any frame from the same origin could otherwise impersonate it.