Best way to "flatten" an array inside an RxJS Observable
You can use concatAll() or mergeAll() without any parameter.
dataFromBackend.pipe( tap(items => console.log(items)), mergeAll(), // or concatAll())This (including mergeMap) works only in RxJS 5 because it treats Observables, arrays, array-like objects, Promises, etc. the same way.
Eventually you could do also:
mergeMap(val => from(val).pipe( tap(item => console.log(item)), map(item => item.name),)),toArray(),Jan 2019: Updated for RxJS 6
Angular 6 note.
If you are using as a pipeable operator, do is known as tap!
https://www.learnrxjs.io/operators/utility/do.htmlHere is an example.
// RxJS import { tap, map, of, mergeMap} from 'rxjs/operators';backendSource .pipe( tap(items => console.log(items)), mergeMap(item => item ), map(item => console.log(item.property)) );