Difference Between The Methods .pipe() And .subscribe() On A Rxjs Observable
I recently notice that I can return a value inside .pipe() but not inside .subscribe(). What is the difference between these two methods? For example if I have this function, let'
Solution 1:
The pipe
method is for chaining observable operators, and the subscribe
is for activating the observable and listening for emitted values.
The pipe
method was added to allow webpack to drop unused operators from the final JavaScript bundle. It makes it easier to build smaller files.
For example if I have this function, let's call it 'deposit', which supposed to return the account balance, if I do this:
deposit(account, amount){ returnthis.http.get('url') .subscribe(res => { return res; } }
It returns an observable
That isn't what it returns. It returns the Subscription
object created when you called Subscribe
.
and if I do this:
deposit(account, amount){ returnthis.http.get('url') .pipe( map(res => { return res; }); ); }
It returns the account balance as expected.
That isn't what it returns. It returns an Observable
which uses a map
operator. The map operator in your example does nothing.
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