Error rxjs_Observable__.Observable.forkJoin is not a function?

Question

I am using Rxjs in an angualr-cli application.

in viewer.component.ts

    //Other Imports
    import { Observable } from 'rxjs/Observable';
    //omitting for brevity
   export class ViewerComponent implements OnInit, AfterViewInit, OnDestroy {
    someFunction(someArg){
    //omitting for brevity
    let someArray: any = [];
    //Add some info
    Observable.forkJoin(someArray).subscribe(data => {
              //Do something with data
            });
    }
    //omitting for brevity
    }  

I get and error as

ERROR TypeError: __WEBPACK_IMPORTED_MODULE_2_rxjs_Observable__.Observable.forkJoin is not a function
    at ViewerComponent.webpackJsonp../src/app/component/viewer.component.ts.ViewerComponent.someFunction(http://localhost:4200/main.bundle.js:4022:73)
    at http://localhost:4200/main.bundle.js:3951:31

But if I Import Rxjs completely (import 'rxjs';) everything works. No error. I cont seem to understand whats additional that needed. I also tries importing rxjs/Observable/forkjoin but nothing to avail.

Any pointers on how to go about this.

Answer 1

As explained here, you have two options:

1. Either import all operators as a single package
2. Or import each operator individually

In the first case you would use import like this:

import Rx from 'rxjs/Rx';

Rx.Observable.forkJoin(1,2,3)

In the second like this:

import { Observable } from 'rxjs/Observable';
import 'rxjs/add/observable/forkJoin';

I believe what you're looking for is the second option.

Answer 2

For RxJS v6.5+, it is now:

import { forkJoin } from 'rxjs';

https://www.learnrxjs.io/operators/combination/forkjoin.html