[nisdec]

On paper you should be able to do the same with a HTML5 manifest file.

Don't get me wrong, it's a really neat wrapper, I'm just curious about why I should use this library instead of an already in HTML5 implemented, easy way which does pretty much the same?

[nilliams]

By HTML5 manifest file, do you mean the Application Cache? Because that is apparently (I've never tried it) anything but an 'easy way' [0]. Whereas this script appears to wrap ServiceWorkers, which is the 'modern', recommended way to do things [1]. Also being a 'neat wrapper' with a simple API is often a good enough reason for something to exist.

[0] http://alistapart.com/article/application-cache-is-a-doucheb...

[1] https://www.youtube.com/watch?v=SdMxGNkZqnU