JS is making a comeback but is slow and uses lots of memory. JS is no-bueno for mobile phones so is limited. To understand the needs, firefox uses it Gecko engine, Chrome and Edge (new 2022) uses Chromium, safari used WebKit… all of them are open source. But which one fill your needs? To me, gecko is the best for pc. I find chrome very limited compared to Firefox. And edge… im glad the Microsoft framework was abandoned in favor of chromium, that makes edge more in-par for standards. WebKit is great, and has all the features as well, but not compared to gecko. In the mobile world, we need to understand that a mobile phone runs on battery and has no fan, all browsers are lite or Watered down. WebKit for apple and chrome for android will not run JS or full python for example… is just common sense.