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

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-douchebag http://alistapart.com/article/application-cache-is-a-doucheb... [1] https://www.youtube.com/watch?v=SdMxGNkZqnU https://www.youtube.com/watch?v=SdMxGNkZqnU