How to Add Custom Data to WooCommerce Order using ajax

Step 1: Masukkan script ajax di footer

add_action( 'wp_footer', 'custom_checkout_script' );
function custom_checkout_script() {
    ?>
    <script type="text/javascript">

$(window).on('load', function() {
   
	$( "#employers_name" ).parent().append( "<button id=\"otherluq\" type=\"button\">Click Me!</button>" );

	
$( "#otherluq" ).click(function() {
  
	$.ajax({
                type: 'POST',
                url: '<?php echo admin_url( 'admin-ajax.php' ) ; ?>',
                data: {action: 'woo_modify_charges'},
                success: function (code) {
                    console.log(code);
                    //jQuery('.woocommerce-error, .woocommerce-message').remove();

                    if (code === '0') {
                        //$form.before(code);
                        $('body').trigger('update_checkout');
                    }
                },
                dataType: 'html'
            });

});



})


	</script>
	<?php
}

Step 2: Panggil Function dari ajax dan simpan session

add_action('wp_ajax_woo_modify_charges', 'etq_calculate', 10);
add_action('wp_ajax_nopriv_woo_modify_charges', 'etq_calculate', 10);
function etq_calculate() {
    global $woocommerce;
  

    if( !isset($_SESSION) ) session_start();
    $_SESSION['addanakluq'] = 500;
}

Step 3: Extract Custom Data from WooCommerce Session and Insert it into Cart Object

add_action( 'woocommerce_review_order_after_submit', 'change_calculated_total', 10, 2 );
function change_calculated_total( $total) {
	print_r("<pre>");
	var_dump($total);
	print_r("</pre>");exit();
	if(!isset($_SESSION)) session_start();

	if(isset($_SESSION['addanakluq'])){
		unset($_SESSION['addanakluq']);
		return $total + 300;
	}else{
		return $total ;
	}
    

   
}