We haven't mentioned it much so far, but the RxJS library weighs in quite heavily when used in an app. In today's world of mobile first, every kilobyte counts when it comes to libraries that you include in your app. They count because the user may be on a 3G connection, and if it takes too long to load, your user may leave, or just may end up not liking your app, as it feels slow to load, and this may cause you to have bad reviews or lose users. So far, we have used two different ways of importing RxJS:
- Importing the whole library; this one is quite costly in terms of size
- Importing only the operators we need; this ensures that the bundle decreases significantly
The different options have looked like this, for importing the whole library and all its operators:
importRxfrom"rxjs/Rx";
Or like this, to only import what we need:
import { Observable } from 'rxjs/Observable';
import "rxjs/add/operator/map";
import "rxjs/add/operator/take";
let stream = Observable.interval(1000)
...