Fix access to the parent triggers security error "CORS" in wordpress.org preview

Author: DevWael

assets/js/src/custom.js

@@ -1813,16 +1813,16 @@ botiga.misc = {
 		}
 	},
 	customizer: function() {
-		if( ! window.parent.document.body.classList.contains( 'wp-customizer' ) ) {
+		if ( typeof wp === 'undefined' || typeof wp.customize === 'undefined' ) {
 			return false;
 		}
 
-		window.onload = function() {
+		wp.customize.bind( 'preview-ready', function() {
 			var cart_count = document.querySelectorAll( '.cart-count' );
 			if( cart_count.length ) {
 				jQuery( document.body ).trigger( 'wc_fragment_refresh' );
 			}
-		}
+		} );
 	}
 }