Google is strongly committed to these technologies because it has seen that every time users are more loyal to mobile applications than websites and have websites that are at the same time mobile applications , it is the best way to turn the tortilla around. However, this is not something new, I wrote a few years ago about web design hong kong being indistinguishable from mobile applications. In fact, all this began to develop in 2005 when the Web Applications 1.0 standard that would later become the HTML5 standard began to be forged within the newly created WHATWG.
It must be responsive : the design must be automatically adapted to any screen resolution. With push notifications : if you still do not know what they are, I advise you to read the entry: Push notifications on your website to increase recurring visits and conversions , since this is one of the most interesting characteristics of PWA, since in addition to a new functionality that can add value to the user, it is a new type of online advertising.
Improved connectivity to work without connection or with poor quality networks. I wrote previously about a technology to do this called Application Cache , but this solution has ended up being discarded because it generates enough problems to correctly manage the updates. So now we must use, service workers , which is a solution that allows any cache strategy implementation that we can imagine (besides that they are also used for push notifications).
For the caching of URLs, the Cache API is used (it uses Cache Storage) and for the rest of the IndexedDB data , it does not use Web Storage (Local Storage and Session Storage), nor any other storage API because they are not accessible from service workers. The space allowed depends on the browser and the available free space. Only large quantities can be stored by asking the user for permission.