如何避免嵌套循环

Question

I need to construct this object wit the has and repo. I feel like nesting these maps is a really bad practice, and it's the point of failure for the flow. How should this be written?

let observ = observable$.flatMap(repos => {
  return Rx.Observable.from(repos.map(repo => ({hash: getHash(repo), repo})))
})

Answer 1

I don't see anything explicitly wrong with this approach. If you would like to simplify the code, you can use concatMap , which will transform a stream of arrays to a stream of the items. We can then just do a normal map:

let repo$ = observable$.concatMap(identity);
let observ = repo$.map(repo => ({hash: getHash(repo), repo }));

Where identity === x => x .

You can also apply concatMap earlier in your chain when constructing the observable$ stream if you want to avoid calling it with identity .