Practical RxJS In The Wild 🦁— Requests with concatMap() vs mergeMap() vs forkJoin() 🥊

Tomas Trajan
Angular In Depth
Published in
8 min readDec 19, 2017

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What? Stream? Did anyone say stream?! (Pipe cat 📷 by Mikhail Vasilyev)

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I would like to share with you experience acquired by working on a yet another Hacker News client (code name HAKAFAKA 😂 still in alpha). I have been on the road for couple months now and realized that a small coding project wouldn’t hurt. And sure it didn’t, on the contrary it provided inspiration for this new post so let’s get straight to it!

Contextual intro

In most of the apps we are building we have to perform at least some requests to the backend. Retrieving data to show it to the user, updating entities, submitting forms or any other activity involving communication with the server.

Retrieving of collections

Most APIs provide endpoints for retrieving whole collections of items with single request. Think users, posts or transactions. For large collections it is usually also possible to retrieve a subset of all items by sending pagination information in query parameters.

When we’re developing our own API we are in full control and we should provide such endpoints because it reduces overhead…

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Tomas Trajan
Angular In Depth

👋 I build, teach, write & speak about #Angular & #NgRx for enterprises 👨‍💻 Google Developer Expert #GDE 👨‍🏫 @AngularZurich meetup co-organizer