This site is entirely unreadable on an iPhone 6s. Not exactly a credible source. The problem seems to be the code blocks.
QuirksMode.org was the best source on the web for most browser DOM events for a decade. It might still be.
Whether they are credible about iPhone X issues, that is TBD.
Peter-Paul Koch is probably the most authoritative source regarding browser quirks outside of browser developers. Don't let a dated website design color your view of the content.