The W3C Roadmap for web application on mobile, (also applies to desktop etc) has finaly published the 2018 version, (a few months later than expected).
Whilst some features are mobile device only, much of what is contained also applies to 'fixed' systems such as desktops. The roadmap gives a good overview of features that are considered stable, and usable, plus an insight to upcoming features.
https://www.w3.org/2018/04/web-roadmaps/mobile/
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