Get option values for JetEngine options pages inside the PHP code

options-values-in-code.php

<?php
/**
 * Method 1
 * Can be used for: Any storage type
 *
 * page-slug - replace this with your Option Page slug
 * option-name - replace this with your option Name/ID
 */
$value = jet_engine()->listings->data->get_option( 'page-slug::option-name' );

/**
 * Method 2
 * Can be used for: Any storage type
 *
 * page-slug - replace this with your Option Page slug
 * option-name - replace this with your option Name/ID
 */
$page  = jet_engine()->options_pages->registered_pages['page-slug'];
$value = $page->get( 'option-name' );

/**
 * Method 3
 * Can be used for: Default storage type
 *
 * page-slug - replace this with your Option Page slug
 * option-name - replace this with your option Name/ID
 */
$all_options = get_option( 'page-slug', array() );
$value       = isset( $all_options['option-name'] ) ? $all_options['option-name'] : false;

/**
 * Method 4
 * Can be used for: Separate storage type + `Add prefix for separate options` is DISABLED
 *
 * option-name - replace this with your option Name/ID
 */
 $value = get_option( 'option-name' );
 
 /**
 * Method 5
 * Can be used for: Separate storage type + `Add prefix for separate options` is ENABLED
 *
 * page-slug - replace this with your Option Page slug
 * option-name - replace this with your option Name/ID
 */
 $value = get_option( 'page-slug_option-name' );

@jwamsterdam @Galibri
There is some update for those who want to use php to update options.
The options inside jetengine is actually save as options in the wp_option table. So the typical get_option and update_option will do.
And the mutiple field value is saved as array.
So let say you have a option page named with slug "dining-certificate-options_copy" and the field slug is "certificate-number"
Just simply:

// getting the whole option array from wp_option
$dinning_cert_option = get_option('dining-certificate-options_copy');
//Only change the value of a item in the array
$dinning_cert_option['certificate-number'] = ' anything';
// simply update the option 
update_option('dining-certificate-options_copy', $dinning_cert_option);	

Hooks are:

jet-engine/options-pages/after-save
jet-engine/options-pages/after-save/PAGE_SLUG
jet-engine/options-pages/updated
jet-engine/options-pages/updated/PAGE_SLUG

The only argument passed to a hook is an instance of Jet_Engine_Options_Page_Factory (\jet-engine\includes\components\options-pages\options-page.php)

I was defining a number of modules for an overview page and then I wanted to render the modules dynamically via Ajax on click. This did not work with the jetengine object as it wasn't available during the "init" or "enqueue_scripts" action hooks.
Method 3 was the solution; I simply got the option values right out of the WordPress database.
Hope this info helps somebody else in the same situation.

@nextab

This did not work with the jetengine object as it wasn't available during the "init" or "enqueue_scripts" action hooks.

it is not available until 'init' with priority of 12 or something like that, just try calling it a bit later

it is not available until 'init' with priority of 12 or something like that, just try calling it a bit later

Thank you for pointing this out. I'm sure this can come in handy at some point in the future.