I wrote a little Trie in Javascript for practice a while back. It flattens the data into a single array for better locality. I think it ends up being pretty quick for lookups (but not insertions).

https://github.com/mgraczyk/fast-trie-js/blob/master/index.j...

I used it for this little demo:

https://assets.opentoken.com/demos/search/index.html