"For example, scroll events fire only after the scroll has finished on mobile browsers"

This is not accurate at all for iOS Safari and Chrome... I just wrote some scroll-based events earlier this week and they work just fine.

There is some good stuff mixed in here but a lot of it is misleading, poorly defined, or just flat-out wrong. The most accurate stuff is extremely common sense like "staging environment should mirror prod" "don't use == (JS)" "don't use doc write (JS)" etc