CODEWITHSUNDEEP
rxjsngrx
Maxim Zhukov
Maxim Zhukov

Reputation: 10140

Pipe and select operators in RxJS

I'm wondering whether the following two blocks of code behave in the same manner:

With pipe (from original ngrx sample):

pending$ = this.store.pipe(select(fromAuth.selectLoginPagePending));
error$ = this.store.pipe(select(fromAuth.selectLoginPageError));

And without one:

pending$ = this.store.select(fromAuth.selectLoginPagePending);
error$ = this.store.select(fromAuth.selectLoginPageError);

I've tested both and haven't noticed any apparent difference.

Thoughts?

Upvotes: 1

Views: 3807

Answers (2)

wentjun
wentjun

Reputation: 42526

Yes, you are right. Both 

pending$ = this.store.pipe(select(fromAuth.selectLoginPagePending));
error$ = this.store.pipe(select(fromAuth.selectLoginPageError));

and 

pending$ = this.store.select(fromAuth.selectLoginPagePending);
error$ = this.store.select(fromAuth.selectLoginPageError);

carry out the same function, which is to obtain a slice of the store state , as described on the NgRX documentation on selectors.

However, the pipe() utility allows you to chain the selector with RxJS pipeable operators, such as scan(), and filter(), allowing you to carry out other operations such as state transitions.

Upvotes: 1

timdeschryver
timdeschryver

Reputation: 15505

They both do the same thing. Internally, the store.select function calls the select operator.

Upvotes: 1

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