Elixir's stdlib is great. It's small, based on a just a handful of concepts, but thanks to how powerful the concepts are it covers a lot of use cases. Every module contains pretty much everything you'd ever need to work with the concept that module implements, be it a String, an Enumerable, a Stream, or anything else in the stdlib.

But, Elixir is cheating. It can stay clean and compact in part because it sits on top of 30 years of development of Erlang stdlib. Erlang stdlib is messy, spread across multiple applications and modules, with module interfaces inconsistent with each other, not to mention parts of it still include compatibility layers for Erlang/OTP version so old that they didn't have lambdas yet. But, the functionality is there, which enables Elixir to have a small, focused stdlib - because when something is missing, you can just grab an Erlang equivalent.

This is similar to what Clojure does on the JVM. JS doesn't have the luxury of sitting on top of a battle tested stdlib, and trying to cover all the functionality of such stdlib is what results in incomplete and unstable APIs and reliance on so many external packages.