The 6 RXJS operators you have to know

1.Concat

Const getpostone$ = Rx.Observable.timer. Mapto ({id:1= Rx.Observable.timer (+). Mapto ({id:2  = = Console.log (res));

Merging multiple observables, when you subscribe one time, the secondary operator merges the results of multiple observable into the obserable of the output.

You can use this operator if your focus is on the order of the output. For example, you can use this operator when you need to send AJAX requests sequentially.

2.forkJoin

Forkjoin is the RX version of the Promise.all () method.

Const getpostone$ = Rx.Observable.timer (+). Mapto ({id:1= Rx.Observable.timer (+). Mapto ({id:2
Print [{id:1}, {id:2}]

Use this operator when you need to run observable concurrently.

3.mergeMap

Const post$ = Rx.Observable.of ({id:1= Rx.Observable.timer (). Mapto ({title: "Post title"= post$. Mergemap (post = getpostinfo$). Subscribe (res = Console.log (res));

First, the two terms in Rx:

1.source observable here refers to post$.

2.inner observable here refers to getpostinfo$.

When the inner observable is emitted, the value is merged into the observable of the output.

4.pairWise

// Tracking the scroll delta rx.observable  ' Scroll ')  = window.pageyoffset)  . pairwise ()  //  pair[1]-pair[0] 

Outputs the current value and the previous value as an array. As above example, when triggering the scroll event you can output [10, 11] [11, 12] [12, 13] ...

5.switchMap

Const clicks$ = Rx.Observable.fromEvent (document, ' click '= Rx.Observable.interval ( innerobservable$)                     = = Console.log (val));

In this example, the interval's subscription will be canceled whenever the document is clicked and a new value will be started.

6.combineLatest

Const clicks$ = Rx.Observable.fromEvent (document, ' click '= Rx.Observable.interval (  innerobservable$)                    = Console.log (val));

If sub-flow a launches new data while waiting for another stream to emit data and the other stream does not send the data, it is merged using the data that is most recently emitted by the sub-stream.

The 6 RXJS operators you have to know