Fixed severe PayPal bug ...

By making sure PayPal’s JavaScript file is included in initial page
load, and if not, throwing an exception, to prevent PayPal from
creating “weird cookies” on host domain.

startup/widgets/micro.widgets.paypal-button.hl

@@ -104,23 +104,9 @@ create-event:micro.widgets.paypal-button
       p5.config.get:x:/-/*?name
 
       /*
-       * Ensuring our PayPal JavaScript file is cached locally.
-       *
-       * Notice, we don't download PayPal "checkout.js" file directly from PayPal, since they
-       * have no CORS HTTP headers on their servers, and this will trigger a JavaScript error
-       * if file is dynamically included during a callback - Which it will be, if the
-       * PayPal widget is shown during an Ajax request.
-       *
-       * Instead we download the file from PayPal, cache it locally, and include our
-       * local version of it.
-       *
-       * Yeah, I know it sucks - But complain to PayPal's crappy developers.
-       * It would be dead simple for them to fix this, without security flaws, by
-       * simply adding a simple fucking CORS HTTP header on their freakin' JS file ...!!
-       *
-       * CAN YOU READ THIS PAYPAL ...??
+       * Ensuring our PayPal JavaScript file is included on page.
        */
-      micro.widgets.paypal-button._ensure-checkout-js
+      micro.widgets.paypal-button.ensure-checkout-js
 
       /*
        * Including JavaScript file necessary to render our button, and our JS
@@ -176,28 +162,25 @@ paypal.Button.render({{
  * Helper file to ensure PayPal's "checkout.js" file is locally cached, to avoid
  * CORS problems.
  */
-create-event:micro.widgets.paypal-button._ensure-checkout-js
+create-event:micro.widgets.paypal-button.ensure-checkout-js
 
   /*
-   * Checking if file is cached locally.
-   *
-   * TODO: Perdiocally (every so often), refresh our locally cached file, in case
-   * PayPal for some reasons should actually want to update their JS file on their servers.
+   * Checking if this is an Ajax Callback, and if it is, and PayPal's JavaScript
+   * file has not already been "ensured", we throw an exception.
    */
   if
-    fetch:x:/0/0?value
-      file-exists:/common/documents/public/checkout.js
-    not
-
-    /*
-     * Fetching file from PayPal and caching it locally.
-     */
-    p5.http.get:"https://www.paypalobjects.com/api/checkout.js"
-    save-file:/common/documents/public/checkout.js
-      src:x:/@p5.http.get/**/content?value
+    p5.web.request.is-ajax-callback
+    if
+      fetch:x:/0/0?value
+        p5.web.viewstate.get:micro.widgets.paypal-button.included
+      not
+      throw:@"You must include PayPal's JS file using [micro.widgets.paypal-button.ensure-checkout-js] in the initial load of your page when using the PayPal widget."
+  p5.web.viewstate.set:micro.widgets.paypal-button.included
+    src:bool:true
 
   /*
-   * Then including locally cached version of file.
+   * Checking for the easy version first, in case this is not a callback, 
+   * we directly include the PayPal JavaScript file from PayPal's servers.
    */
-  p5.web.include-javascript-file:/common/documents/public/checkout.js
+  p5.web.include-javascript-file:@"https://www.paypalobjects.com/api/checkout.js"