Let's look at the most popular JS books over the past decade. * JS modules are in the seminal "Javascript: The Good Parts". * "Eloquent Javascript" has an ent

Let's look at the most popular JS books over the past decade. * JS modules are in the seminal "Javascript: The Good Parts". * "Eloquent Javascript" has an entire chapter called "modules" and that has existed across all three versions * "Javascript: The Definitive Guide" also has a section on modules. * Javascript.info contains an entire section about modules. * "Exploring JS" contains a section on the module pattern. * "You Don't Know JS" has even more about it. I don't see how someone could know JS as a senior or even mid-level developer without having read at least one of these sources let alone the years-long barrage of blog articles. I can say with 100% certainty that you cannot write properly using any modern framework without understanding closures (of which modules are one of the easiest patterns). That's not "being purist". That's not requiring everyone to read the latest ECMAScript spec. That's a simple acknowledgement of the day-to-day reality of the job in a typical company.