Examples of how to trigger a custom JavaScript function when Connected Caldera Forms advances or goes back in the connected forms sequence. See: https://calderaforms.com/doc/triggering-javascript-connected-caldera-forms-changes-forms/

cf_form_connector_return_data.php

<?php
/**
* Send additional data back to the browser when connected forms advances
*/
add_filter( 'cf_form_connector_return_data', function( $data ) {
	
	//check if right form
	//Change form ID for connected form
	if ( 'cf1234567' == $data[ 'connected_form_id' ] ) {
		//Get data from a field
		$field_data               = Caldera_Forms::get_field_data( //field ID for field you want data from
			'fld1234567', //form configuration for connected form
			Caldera_Forms_Forms::get_form( $data[ 'connected_form_id' ] ), //entry ID for connected form
			$data[ 'entry_id' ] );

		//add to field data to return data
		$data[ 'something' ]      = $field_data;

		//add something else to return data
		$data[ 'something_else' ] = 'Hi Ron';

	}

	return $data;

});

connect-forms-js-event-data.js

jQuery( document ).on( 'cf.connected', function (event, data ) {
	 
  	//the ID of the connected form
	var connected_form_id = data.connected_form_id;
  
  	//the id attribute of the container the connected form is loaded in
  	var target = data.target;
  
  	//Type of connection. Will be advance or back
  	var type = data.type;
});