Well, you can pass around function pointers, return function pointers, and store function pointers in data structures in C, too. You can also use closures - a closure is just a (function pointer, struct with its closure values) struct. Sure, OCaml, Scheme, and company box the pair for you, garbage collect it, and don't make you flatten your code into a single file-level scope, but the difference between Javascript and C isn't as big as you think.

Javascript is kinda sorta maybe functional if you look at it right, but it's still mostly the same imperative/object-oriented mishmash as Java, Python, or Ruby.