catch

signature: catch(project : function): Observable

Gracefully handle errors in an observable sequence.


:warning: Remember to return an observable from the catch function!


Examples

( example tests )

Example 1: Catching error from observable

( jsBin | jsFiddle )

//emit error
const source = Rx.Observable.throw('This is an error!');
//gracefully handle error, returning observable with error message
const example = source.catch(val => Rx.Observable.of(`I caught: ${val}`));
//output: 'I caught: This is an error'
const subscribe = example.subscribe(val => console.log(val));
Example 2: Catching rejected promise

( jsBin | jsFiddle )

//create promise that immediately rejects
const myBadPromise = () => new Promise((resolve, reject) => reject('Rejected!'));
//emit single value after 1 second
const source = Rx.Observable.timer(1000);
//catch rejected promise, returning observable containing error message
const example = source.flatMap(() => Rx.Observable
                                       .fromPromise(myBadPromise())
                                       .catch(error => Rx.Observable.of(`Bad Promise: ${error}`))
                                    );
//output: 'Bad Promise: Rejected'
const subscribe = example.subscribe(val => console.log(val));

Additional Resources


:file_folder: Source Code: https://github.com/ReactiveX/rxjs/blob/master/src/operator/catch.ts

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