Improve checkout UX (#6248)

payments/templates/includes/braintree_checkout.js

@@ -42,6 +42,14 @@ $(document).ready(function() {
 				})
 			});
 		});
+
+		instance.on('paymentMethodRequestable', function (event) {
+			button.removeAttribute('disabled');
+		});
+
+		instance.on('noPaymentMethodRequestable', function () {
+			button.setAttribute('disabled', true);
+		});
 	});
 
 })

payments/templates/pages/braintree_checkout.html

@@ -26,7 +26,7 @@
 				</div>
 			</section>
 
-			<button class="btn btn-primary" type="submit" id="submit-button"><span>{{ _("Pay") }} {{ amount }} {{ currency }}</span></button>
+			<button class="btn btn-primary" type="submit" id="submit-button" disabled><span>{{ _("Pay") }} {{ amount }} {{ currency }}</span></button>
 		</form>
 
 	</div>