Add checkout form validation to subscriptions.

modules/ppcp-button/resources/js/modules/ActionHandler/CheckoutActionHandler.js

@@ -2,6 +2,7 @@ import 'formdata-polyfill';
 import onApprove from '../OnApproveHandler/onApproveForPayNow.js';
 import {payerData} from "../Helper/PayerData";
 import {getCurrentPaymentMethod} from "../Helper/CheckoutMethodState";
+import validateCheckoutForm from "../Helper/CheckoutFormValidation";
 
 class CheckoutActionHandler {
 
@@ -13,7 +14,13 @@ class CheckoutActionHandler {
 
     subscriptionsConfiguration() {
         return {
-            createSubscription: (data, actions) => {
+            createSubscription: async (data, actions) => {
+                try {
+                    await validateCheckoutForm(this.config);
+                } catch (error) {
+                    throw {type: 'form-validation-error'};
+                }
+
                 return actions.subscription.create({
                     'plan_id': this.config.subscription_plan_id
                 });

modules/ppcp-button/resources/js/modules/Helper/CheckoutFormValidation.js

@@ -0,0 +1,48 @@
+import Spinner from "./Spinner";
+import FormValidator from "./FormValidator";
+import ErrorHandler from "../ErrorHandler";
+
+const validateCheckoutForm = function (config) {
+    return new Promise(async (resolve, reject) => {
+        try {
+            const spinner = new Spinner();
+            const errorHandler = new ErrorHandler(
+                config.labels.error.generic,
+                document.querySelector('.woocommerce-notices-wrapper')
+            );
+
+            const formSelector = config.context === 'checkout' ? 'form.checkout' : 'form#order_review';
+            const formValidator = config.early_checkout_validation_enabled ?
+                new FormValidator(
+                    config.ajax.validate_checkout.endpoint,
+                    config.ajax.validate_checkout.nonce,
+                ) : null;
+
+            if (!formValidator) {
+                resolve();
+                return;
+            }
+
+            formValidator.validate(document.querySelector(formSelector)).then((errors) => {
+                if (errors.length > 0) {
+                    spinner.unblock();
+                    errorHandler.clear();
+                    errorHandler.messages(errors);
+
+                    // fire WC event for other plugins
+                    jQuery( document.body ).trigger( 'checkout_error' , [ errorHandler.currentHtml() ] );
+
+                    reject();
+                } else {
+                    resolve();
+                }
+            });
+
+        } catch (error) {
+            console.error(error);
+            reject();
+        }
+    });
+}
+
+export default validateCheckoutForm;