[RxJS] Use groupBy in real RxJS applications

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This lesson will show when to apply groupBy in the real world. This RxJS operator is best suited when a source observable represents many data sources, e.g. an observable for multitouch events.

 

const busObservable = Rx.Observable.of(  {code: ‘en-us‘, value: ‘-TEST-‘},  {code: ‘en-us‘, value: ‘hello‘},  {code: ‘es‘, value: ‘-TEST-‘},  {code: ‘en-us‘, value: ‘amazing‘},  {code: ‘pt-br‘, value: ‘-TEST-‘},  {code: ‘pt-br‘, value: ‘olá‘},  {code: ‘es‘, value: ‘hola‘},  {code: ‘es‘, value: ‘mundo‘},  {code: ‘en-us‘, value: ‘world‘},  {code: ‘pt-br‘, value: ‘mundo‘},  {code: ‘es‘, value: ‘asombroso‘},  {code: ‘pt-br‘, value: ‘maravilhoso‘}).concatMap(x => Rx.Observable.of(x).delay(500));const all = busObservable  .groupBy(obj => obj.code) // 2-d obs  .mergeMap(innerObs => innerObs.skip(1).map(obj => obj.value));all.subscribe(x => console.log(x));

/*"hello""amazing""olá""hola""mundo""world""mundo""asombroso""maravilhoso"*/

 

• The ‘groupBy‘ return a 2-d observable, can use ‘switchMap‘ or ‘mergeMap‘ to conver to 1-d observable.

 

[RxJS] Use groupBy in real RxJS applications