function
stable
Catches errors on the observable to be handled by returning a new observable or throwing an error.
catchError<T, O extends ObservableInput<any>>(selector: (err: any, caught: Observable<T>) => O): OperatorFunction<T, T | ObservedValueOf<O>>
selector | a function that takes as arguments |
OperatorFunction<T, T | ObservedValueOf<O>>
: An observable that originates from either the source or the observable returned by the catch selector
function.
Continues with a different Observable when there's an error
import { of } from 'rxjs'; import { map, catchError } from 'rxjs/operators'; of(1, 2, 3, 4, 5).pipe( map(n => { if (n === 4) { throw 'four!'; } return n; }), catchError(err => of('I', 'II', 'III', 'IV', 'V')), ) .subscribe(x => console.log(x)); // 1, 2, 3, I, II, III, IV, V
Retries the caught source Observable again in case of error, similar to retry() operator
import { of } from 'rxjs'; import { map, catchError, take } from 'rxjs/operators'; of(1, 2, 3, 4, 5).pipe( map(n => { if (n === 4) { throw 'four!'; } return n; }), catchError((err, caught) => caught), take(30), ) .subscribe(x => console.log(x)); // 1, 2, 3, 1, 2, 3, ...
Throws a new error when the source Observable throws an error
import { of } from 'rxjs'; import { map, catchError } from 'rxjs/operators'; of(1, 2, 3, 4, 5).pipe( map(n => { if (n === 4) { throw 'four!'; } return n; }), catchError(err => { throw 'error in source. Details: ' + err; }), ) .subscribe( x => console.log(x), err => console.log(err) ); // 1, 2, 3, error in source. Details: four!
© 2015–2018 Google, Inc., Netflix, Inc., Microsoft Corp. and contributors.
Code licensed under an Apache-2.0 License. Documentation licensed under CC BY 4.0.
https://rxjs.dev/api/operators/catchError