Example code for passing an ACF options page variable to JavaScript through the wp_admin_footer

dynamic-option-fields.js

// holder is the ID of the invisible Div that holds the option field.

// Function to find the option_test text field and populate it with data that is echoed in the option_holder div

jQuery(document).ready(function () {
    var option_populate_FIELD_NAME = document.getElementById('acf-field_58b2d845dda65');
    var option_holder_FIELD_NAME = jQuery('#option_holder_FIELD_NAME');
    var option_test_FIELD_NAME = option_holder_FIELD_NAME["0"].innerText;

    // Checks that the field is empty before populating
    if (option_populate_FIELD_NAME.value == "") {
        option_populate_FIELD_NAME.value = option_FIELD_NAME;
    }
});

// Function to find the option_test_wysiwyg WYSIWYG editor field and populate it with data that is echoed in the option_holder div
jQuery(document).ready(function () {

    // Iframe takes longer to load than the rest of the page - wait a second
    setTimeout(function () {

        //Searches the page for the relevant iFrame
        var option_holder_FIELD_NAME_wysiwyg = jQuery('#option_holder_wysiwyg');
        var option_test_FIELD_NAMEe_wysiwyg = option_holder_wysiwyg["0"].innerText;
        var option_populate_FIELD_NAME_id = document.querySelector('#mceu_146');
        var iframe = option_populate_FIELD_NAME_id.querySelector('iframe');
        //console.log(iframe)

        var iframeDocument = iframe.contentDocument || iframe.contentWindow.document;
        //console.log(iframeDocument);

        var option_populate_FIELD_NAME_wysiwyg = iframeDocument.querySelector('body');
        //console.log(option_populate_wysiwyg);

        // Append item
        option_populate_FIELD_NAME.append(option_FIELD_NAME);

        //console.log(option_populate_wysiwyg.firstChild);

    }, 1000);
    
});

functions.php

// Enable options page
if( function_exists('acf_add_options_page') ) {
	acf_add_options_page();
}

// Custom WordPress Footer
function remove_footer_admin () {

		// Each empty div holds a php varible
		echo '<div id="option_holder_FIELD_NAME" style="display:none">'; the_field('field_name', 'option'); echo '</div>';
		echo '<div id="option_holder_FIELD_NAME_wysiwyg" style="display:none">'; the_field('field_name_wysiwyg', 'option'); echo '</div>';
}

// Enqueues scripts in specified CPT admin area

function add_admin_scripts( $hook ) {
    global $post;
    if ( $hook == 'post-new.php' || $hook == 'post.php' ) {
        if ( 'city' === $post->post_type ) { 

			// Enqueues JavaScript			    
            wp_enqueue_script(  'myscript', get_stylesheet_directory_uri().'/assets/js/dynamic-option-fields.js' );

			// Enqueues Custom Footer
			add_filter('admin_footer_text', 'remove_footer_admin');
        }
    }
}

// Calls admin scripts function
add_action( 'admin_enqueue_scripts', 'add_admin_scripts', 10, 1 );

Fields are created on the options page and the post page.