you can do it like this too: let solution = (s)=> !!Number(s) && (s.length == 4 || s.length == 6)

you probably send it with get method , as you maybe know max allowed length of a url is 2000. you should send it within a json via post method instead

Daily Dev Tips best way to find out why nest.js is better is trying it ! but i can say that deno is runtime environment but nestjs is an entire framework. just google it and read docs. you won't regret it

i haven't used it yet but i think nest.js is better and more powerful