Events — Maxforms Developers

The SDK emits events as the form progresses through its lifecycle. Subscribe with Maxforms('on', ...).

Event vocabulary#

Event	Payload fields	Fires when
`maxforms.form.loaded`	`formId, embedId, page`	Form has rendered inside the iframe.
`maxforms.form.page_view`	`formId, embedId, page`	User moved to a new page of a multi-page form.
`maxforms.form.redirect`	`formId, embedId, url`	The form finished and is redirecting the respondent to the owner's URL; the SDK starts that navigation, then calls your listeners before the page unloads.
`maxforms.form.submitted`	`formId, embedId, submissionId, page`	Submission persisted successfully.
`maxforms.form.resize`	`formId, embedId, height`	The form's content height changed (drives dynamic height).
`maxforms.form.overlay_opened`	`formId, embedId`	The form opened a dialog (such as a consent document reader). The SDK expands the iframe over your page until the dialog closes.
`maxforms.form.overlay_closed`	`formId, embedId`	The dialog closed and the iframe is back in its place on your page.

Those seven are the complete set the SDK emits today. maxforms.form.error, maxforms.popup.opened and maxforms.popup.closed are reserved names: they are accepted by Maxforms('on', ...) but nothing dispatches them yet, so do not build on them.

Routing by embedId#

When a page hosts multiple embeds of the same form, each gets a unique embedId (mf_1, mf_2, …). Filter on payload.embedId if you need to distinguish them.

Maxforms('on', 'maxforms.form.submitted', function (p) {
  if (p.embedId === 'mf_1') {
    analytics.track('Hero form submitted', { formId: p.formId });
  }
});

Security notes#

Events arrive over postMessage. The SDK validates the origin before dispatching, so events from any window other than https://form.maxforms.com are ignored. Your handlers can trust the payload object's shape, but do not trust submissionId for authentication: it's intended as a client-side correlation key, not a credential.