For future reference: the preflight request must return these headers: Access-Control-Allow-Origin: * Access-Control-Allow-Methods: GET, POST, HEAD, OPTIONS Access-Control-Allow-Headers: Origin, X-Requested-With, Content-Type, Accept, Authorization, Pragma, Cache-Control Otherwise, Safari will refuse requests made inside a service worker reporting a preflight check fail.  | 
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| .. | ||
| back.js | ||
| items.js | ||
| tabs.js | ||
| worker.js | ||