HubSpot

Note: the hubspot form object could be either "HubspotFormsV4" or "HubSpotForms", this can bee seen in console

Tracking In Tag Manager

<script>
window.dataLayer = window.dataLayer || [];

//listener for older version (v3) of HS forms
window.addEventListener('message', function(event) {
	if( event.data.type === 'hsFormCallback' && event.data.eventName === 'onFormSubmitted' ) {
		window.dataLayer.push({
		event: 'form_submission',
		form_id: event.data.id,
		conversion_id: event.data.data.conversionId,
		form_data: event.data.data.submissionValues,
	});
}
});

//listener for v4 HS forms 
window.addEventListener('hs-form-event:on-submission:success', function(event) {
	var hsform = HubspotFormsV4.getFormFromEvent(event);
	if (hsform) {
	hsform.getFormFieldValues().then(function(fieldValues) {
		var transformedData = fieldValues.reduce(function(obj, item) {
		var key = item.name.split('/')[1]; 
		if (key) {
			obj[key] = item.value;
		}
		return obj;
		}, {});

		window.dataLayer.push({
			event: "form_submission",
			form_id: hsform.getFormId(),
			conversion_id: hsform.getConversionId(),
			form_data: transformedData,
		});
	});
	}
});
</script>