rxjs/src/operator/withLatestFrom.ts

Reactive Extensions for modern JavaScript

import { Observable, ObservableInput } from '../Observable';
import { withLatestFrom as higherOrder } from '../operators/withLatestFrom';

/* tslint:disable:max-line-length */
export function withLatestFrom<T, R>(this: Observable<T>, project: (v1: T) => R): Observable<R>;
export function withLatestFrom<T, T2, R>(this: Observable<T>, v2: ObservableInput<T2>, project: (v1: T, v2: T2) => R): Observable<R>;
export function withLatestFrom<T, T2, T3, R>(this: Observable<T>, v2: ObservableInput<T2>, v3: ObservableInput<T3>, project: (v1: T, v2: T2, v3: T3) => R): Observable<R>;
export function withLatestFrom<T, T2, T3, T4, R>(this: Observable<T>, v2: ObservableInput<T2>, v3: ObservableInput<T3>, v4: ObservableInput<T4>, project: (v1: T, v2: T2, v3: T3, v4: T4) => R): Observable<R>;
export function withLatestFrom<T, T2, T3, T4, T5, R>(this: Observable<T>, v2: ObservableInput<T2>, v3: ObservableInput<T3>, v4: ObservableInput<T4>, v5: ObservableInput<T5>, project: (v1: T, v2: T2, v3: T3, v4: T4, v5: T5) => R): Observable<R>;
export function withLatestFrom<T, T2, T3, T4, T5, T6, R>(this: Observable<T>, v2: ObservableInput<T2>, v3: ObservableInput<T3>, v4: ObservableInput<T4>, v5: ObservableInput<T5>, v6: ObservableInput<T6>, project: (v1: T, v2: T2, v3: T3, v4: T4, v5: T5, v6: T6) => R): Observable<R> ;
export function withLatestFrom<T, T2>(this: Observable<T>, v2: ObservableInput<T2>): Observable<[T, T2]>;
export function withLatestFrom<T, T2, T3>(this: Observable<T>, v2: ObservableInput<T2>, v3: ObservableInput<T3>): Observable<[T, T2, T3]>;
export function withLatestFrom<T, T2, T3, T4>(this: Observable<T>, v2: ObservableInput<T2>, v3: ObservableInput<T3>, v4: ObservableInput<T4>): Observable<[T, T2, T3, T4]>;
export function withLatestFrom<T, T2, T3, T4, T5>(this: Observable<T>, v2: ObservableInput<T2>, v3: ObservableInput<T3>, v4: ObservableInput<T4>, v5: ObservableInput<T5>): Observable<[T, T2, T3, T4, T5]>;
export function withLatestFrom<T, T2, T3, T4, T5, T6>(this: Observable<T>, v2: ObservableInput<T2>, v3: ObservableInput<T3>, v4: ObservableInput<T4>, v5: ObservableInput<T5>, v6: ObservableInput<T6>): Observable<[T, T2, T3, T4, T5, T6]> ;
export function withLatestFrom<T, R>(this: Observable<T>, ...observables: Array<ObservableInput<any> | ((...values: Array<any>) => R)>): Observable<R>;
export function withLatestFrom<T, R>(this: Observable<T>, array: ObservableInput<any>[]): Observable<R>;
export function withLatestFrom<T, R>(this: Observable<T>, array: ObservableInput<any>[], project: (...values: Array<any>) => R): Observable<R>;
/* tslint:enable:max-line-length */

/**
 * Combines the source Observable with other Observables to create an Observable
 * whose values are calculated from the latest values of each, only when the
 * source emits.
 *
 * <span class="informal">Whenever the source Observable emits a value, it
 * computes a formula using that value plus the latest values from other input
 * Observables, then emits the output of that formula.</span>
 *
 * <img src="./img/withLatestFrom.png" width="100%">
 *
 * `withLatestFrom` combines each value from the source Observable (the
 * instance) with the latest values from the other input Observables only when
 * the source emits a value, optionally using a `project` function to determine
 * the value to be emitted on the output Observable. All input Observables must
 * emit at least one value before the output Observable will emit a value.
 *
 * @example <caption>On every click event, emit an array with the latest timer event plus the click event</caption>
 * var clicks = Rx.Observable.fromEvent(document, 'click');
 * var timer = Rx.Observable.interval(1000);
 * var result = clicks.withLatestFrom(timer);
 * result.subscribe(x => console.log(x));
 *
 * @see {@link combineLatest}
 *
 * @param {ObservableInput} other An input Observable to combine with the source
 * Observable. More than one input Observables may be given as argument.
 * @param {Function} [project] Projection function for combining values
 * together. Receives all values in order of the Observables passed, where the
 * first parameter is a value from the source Observable. (e.g.
 * `a.withLatestFrom(b, c, (a1, b1, c1) => a1 + b1 + c1)`). If this is not
 * passed, arrays will be emitted on the output Observable.
 * @return {Observable} An Observable of projected values from the most recent
 * values from each input Observable, or an array of the most recent values from
 * each input Observable.
 * @method withLatestFrom
 * @owner Observable
 */
export function withLatestFrom<T, R>(this: Observable<T>, ...args: Array<ObservableInput<any> | ((...values: Array<any>) => R)>): Observable<R> {
  return higherOrder(...args)(this);
}