> Mastery of what? Most of them are trivia questions. They don't concern any fundamental knowledge or capability, just familiarity with some arbitrary aspect of

> Mastery of what? Most of them are trivia questions. They don't concern any fundamental knowledge or capability, just familiarity with some arbitrary aspect of browser's working or even a particular JS library. I can think of a lot of cases in front-end programming where knowing the volumes of trivia is very important/useful and can very well be considered a job in itself (and often is). It's precisely the reason why I'm moving away from most of it for the time being, because I feel it's just too much trivia and too little 'fundamental knowledge or capability'. The latter ages well, the former doesn't. However, I don't think they're just trivia questions. If you want to create a web app that supports a good range of devices, multiple browsers on these devices, and all the various quirks that exist until this moment, do you really want your 'master' developers to memorize this trivia? The same goes for CSS and its quirks, and quite a lot of js/dom stuff. It's getting better, but there's still a staggering amount of trivia to learn, and there's immense value in the kind of person who would willingly learn all this.