work.suroh.tk/node_modules/rxjs/_esm2015/operator/catch.js

64 lines
2.0 KiB
JavaScript

import { catchError as higherOrder } from '../operators/catchError';
/**
* Catches errors on the observable to be handled by returning a new observable or throwing an error.
*
* <img src="./img/catch.png" width="100%">
*
* @example <caption>Continues with a different Observable when there's an error</caption>
*
* Observable.of(1, 2, 3, 4, 5)
* .map(n => {
* if (n == 4) {
* throw 'four!';
* }
* return n;
* })
* .catch(err => Observable.of('I', 'II', 'III', 'IV', 'V'))
* .subscribe(x => console.log(x));
* // 1, 2, 3, I, II, III, IV, V
*
* @example <caption>Retries the caught source Observable again in case of error, similar to retry() operator</caption>
*
* Observable.of(1, 2, 3, 4, 5)
* .map(n => {
* if (n === 4) {
* throw 'four!';
* }
* return n;
* })
* .catch((err, caught) => caught)
* .take(30)
* .subscribe(x => console.log(x));
* // 1, 2, 3, 1, 2, 3, ...
*
* @example <caption>Throws a new error when the source Observable throws an error</caption>
*
* Observable.of(1, 2, 3, 4, 5)
* .map(n => {
* if (n == 4) {
* throw 'four!';
* }
* return n;
* })
* .catch(err => {
* throw 'error in source. Details: ' + err;
* })
* .subscribe(
* x => console.log(x),
* err => console.log(err)
* );
* // 1, 2, 3, error in source. Details: four!
*
* @param {function} selector a function that takes as arguments `err`, which is the error, and `caught`, which
* is the source observable, in case you'd like to "retry" that observable by returning it again. Whatever observable
* is returned by the `selector` will be used to continue the observable chain.
* @return {Observable} An observable that originates from either the source or the observable returned by the
* catch `selector` function.
* @method catch
* @name catch
* @owner Observable
*/
export function _catch(selector) {
return higherOrder(selector)(this);
}
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