es6/observable/combineLatest.js

import { isScheduler } from '../util/isScheduler';
import { isArray } from '../util/isArray';
import { ArrayObservable } from './ArrayObservable';
import { CombineLatestOperator } from '../operator/combineLatest';
/* tslint:enable:max-line-length */
/**
 * Combines multiple Observables to create an Observable whose values are
 * calculated from the latest values of each of its input Observables.
 *
 * <span class="informal">Whenever any input Observable emits a value, it
 * computes a formula using the latest values from all the inputs, then emits
 * the output of that formula.</span>
 *
 * <img src="./img/combineLatest.png" width="100%">
 *
 * `combineLatest` combines the values from all the Observables passed as
 * arguments. This is done by subscribing to each Observable, in order, and
 * collecting an array of each of the most recent values any time any of the
 * input Observables emits, then either taking that array and passing it as
 * arguments to an optional `project` function and emitting the return value of
 * that, or just emitting the array of recent values directly if there is no
 * `project` function.
 *
 * @example <caption>Dynamically calculate the Body-Mass Index from an Observable of weight and one for height</caption>
 * var weight = Rx.Observable.of(70, 72, 76, 79, 75);
 * var height = Rx.Observable.of(1.76, 1.77, 1.78);
 * var bmi = Rx.Observable.combineLatest(weight, height, (w, h) => w / (h * h));
 * bmi.subscribe(x => console.log('BMI is ' + x));
 *
 * @see {@link combineAll}
 * @see {@link merge}
 * @see {@link withLatestFrom}
 *
 * @param {Observable} observable1 An input Observable to combine with the
 * source Observable.
 * @param {Observable} observable2 An input Observable to combine with the
 * source Observable. More than one input Observables may be given as argument.
 * @param {function} [project] An optional function to project the values from
 * the combined latest values into a new value on the output Observable.
 * @param {Scheduler} [scheduler=null] The Scheduler to use for subscribing to
 * each input 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.
 * @static true
 * @name combineLatest
 * @owner Observable
 */
export function combineLatest() {
    var observables = [];
    for (var _i = 0; _i < arguments.length; _i++) {
        observables[_i - 0] = arguments[_i];
    }
    var project = null;
    var scheduler = null;
    if (isScheduler(observables[observables.length - 1])) {
        scheduler = observables.pop();
    }
    if (typeof observables[observables.length - 1] === 'function') {
        project = observables.pop();
    }
    // if the first and only other argument besides the resultSelector is an array
    // assume it's been called with `combineLatest([obs1, obs2, obs3], project)`
    if (observables.length === 1 && isArray(observables[0])) {
        observables = observables[0];
    }
    return new ArrayObservable(observables, scheduler).lift(new CombineLatestOperator(project));
}
//# sourceMappingURL=combineLatest.js.map