Martin Sikora 9105005192 refactor(router): refactor and simplify router RxJS chains (#40290)
Refactor and simplifiy RxJS usage in the router package
in order to reduce its size and increase performance.

PR Close #40290
2021-01-11 15:30:55 -08:00

28 lines
934 B
TypeScript

/**
* @license
* Copyright Google LLC All Rights Reserved.
*
* Use of this source code is governed by an MIT-style license that can be
* found in the LICENSE file at https://angular.io/license
*/
import {from, MonoTypeOperatorFunction, ObservableInput, of} from 'rxjs';
import {map, switchMap} from 'rxjs/operators';
/**
* Perform a side effect through a switchMap for every emission on the source Observable,
* but return an Observable that is identical to the source. It's essentially the same as
* the `tap` operator, but if the side effectful `next` function returns an ObservableInput,
* it will wait before continuing with the original value.
*/
export function switchTap<T>(next: (x: T) => void|ObservableInput<any>):
MonoTypeOperatorFunction<T> {
return switchMap(v => {
const nextResult = next(v);
if (nextResult) {
return from(nextResult).pipe(map(() => v));
}
return of(v);
});
}