Redirect to checkout page after appointment made

app-redirect-to-checkout-page.php

<?php
//Requires App+ and MarketPress
add_action( 'wp_footer', function(){

	global $post;

	if( ! $post instanceof WP_Post || strpos( $post->post_content, '[app_' ) === false || ! function_exists('mp_store_page_url') ){
		return;
	}

	$checkout_page = mp_store_page_url( 'checkout', false );
	?>

	<script type="text/javascript">
	(function($){

		var WPMUDEV_App_Post_Confirm = {
			load: function(){
				$( document ).ajaxComplete(function( event, xhr, settings ) {				  
					var action = WPMUDEV_App_Post_Confirm.get_action( 'action', settings.data );
					var response = JSON.parse(xhr.responseText);
					if( action == 'post_confirmation' && typeof response.error === 'undefined' ){
						document.location="<?php echo $checkout_page; ?>";
					}

				});
			},
			get_action: function(name, url){
				if (!url){
					return '';
				}
			    name = name.replace(/[\[\]]/g, "\\$&");
			    //var regex = new RegExp("[?&]" + name + "(=([^&#]*)|&|#|$)"),
			    var regex = new RegExp(name + "(=([^&#]*)|&|#|$)"),
			        results = regex.exec(url);
			    if (!results) return null;
			    if (!results[2]) return '';
			    return decodeURIComponent(results[2].replace(/\+/g, " "));				
			}
		};


		$( document ).ready(function(){
			WPMUDEV_App_Post_Confirm.load();	
		});
	})(jQuery);
	</script>

	<?php
}, 10 );