TypeScript won. I was watching this video by Evan Czaplicki the creator [0], and what struck me was that back then, Evan was absolutely right. He was right that in the high level, we needed a typed JS, but he was wrong in the lower level details, at least in terms of market share. TypeScript won precisely because it doesn't start off as intimidating for JS users, while others like Reason and Elm died off, but ironically TS is way more complex than either of the others in its type system.

Another factor for this is that Syntax Matters™. When Gleam (language on the Erland runtime, cousin of Elixir) started out, it had a Haskell-like syntax, but this was found to be a barrier for adoption, so when the creator changed it to be more C and Rust-like, the adoption rate picked up significantly [1]. In the same vein, perhaps Elm was just too esoteric for those coming from JS. I strongly believe the reason Rust became so popular is that it's an ML in C clothing, rather than being a pure ML like OCaml. With curly braces and all, it's more accessible and then people start learning about the more functional features like maps, folds, and so on.

Elm also had quite a rocky history with the BDFL not allowing other people to use the features the compiler maintainers could use, such as escape hatches, which are documented in other parts of HN. This article [2] is a particularly good overview of why some people left.

[0] https://www.youtube.com/watch?v=oYk8CKH7OhE

[1] https://news.ycombinator.com/item?id=22902462#22903210

[2] https://news.ycombinator.com/item?id=22821447