The call to untar in this case is actually totally synchronous so all the callbacks arrive before the async handler resolves. I modified the library which did use a Web Worker... anyway, the callback is fairly misleading- I'll fix it up.
Gotcha about the callback. But the cache.put() part could definitely fail asynchronously, which is not uncommon if you're, for instance, out of storage quota for your origin.
We're a place where coders share, stay up-to-date and grow their careers.
We strive for transparency and don't collect excess data.