Solution:
You can use jQuery to achieve your result.
Approach :
WooCommerce
fires a jQuery event updated_checkout
nearly every time when anything happens on to the checkout page. So you can use that event to achieve your desired result.
Modification in your current code :
1) First of all add JS
so that we can do jQuery
coding in that JS File.
So after Modification your code will look something like this :
customPlugin.php
<?php
/*
* Plugin Name: Hook Priority
*
*/
function add_my_shortcode() {
ob_start();
global $woocommerce;
echo $woocommerce->cart->discount_cart;
return ob_get_clean();
}
add_shortcode('my_shortcode', 'add_my_shortcode');
function add_message_in_checkout() {
//var_dump(do_shortcode('[my_shortcode]'));
/*Modification*/
echo '<div class="coupon_value">'.do_shortcode('[my_shortcode]').'</div>'; // Here I have modified it to give class and update value
}
add_action('woocommerce_before_checkout_form', 'add_message_in_checkout');
function coupon_removed_function( $coupon_code ) {
remove_all_actions('woocommerce_before_checkout_form');
remove_shortcode('my_shortcode');
do_action('woocommerce_before_checkout_form');
}
add_action("woocommerce_removed_coupon", 'coupon_removed_function');
/*Modifications starts from here*/
/*Action to enqueue Jjavascript in Footer*/
add_action("wp_footer", 'enqueue_plugin_script');
function enqueue_plugin_script(){
/*Enqueue Custom Javascript to use*/
wp_enqueue_script( 'custom-script', plugin_dir_url( __FILE__ ).'custom.js', array( 'jquery' ), '1.0.0', true );
/*Localize parameter to use in JS file*/
wp_localize_script( 'custom-script', 'custom_values', array(
'ajaxurl' => admin_url( 'admin-ajax.php' ),
'token' => wp_create_nonce( 'token' )
));
}
/*AJAX Event to check for discount*/
add_action('wp_ajax_check_for_coupon', 'check_for_coupon');
add_action('wp_ajax_nopriv_check_for_coupon', 'check_for_coupon');
function check_for_coupon(){
global $woocommerce;
$send_json = array();
$send_json = array('success'=>false);
if($woocommerce->cart->discount_cart){
$send_json = array('success'=>true, 'discount'=>$woocommerce->cart->discount_cart);
}
wp_send_json($send_json);
die();
}
custom.js
/*
* custom.js
* @author : Rohil Mistry
*/
(function($){
$(document).ready(function(){
/*updated_checkout event*/
$(document.body).on('updated_checkout', function(){
/*Make an AJAX call on updated_checkout event*/
$.ajax({
type: 'POST',
url: custom_values.ajaxurl,
data: {action:'check_for_coupon'},
success: function( result ) {
console.info(result);
if(result.success){
$(".coupon_value").html(result.discount);
}
else{
$(".coupon_value").html('');
}
}
});
});
});
})(jQuery);
Find my Inline comment in code to understand the code.
Let me know if you have any doubt.