groupBy() is another RxJS operator to create higher order observables. In this lesson we will learn how groupBy works for routing source values into different groups according to a calculated key.
const numbersObservable = Rx.Observable.interval(500).take(5); numbersObservable .groupBy(x => x % 2) .map(innerObs => innerObs.count()) .mergeAll() .subscribe(x => console.log(x)); /* --0--1--2--3--4| groupBy(x => x % 2) --+--+---------| \ \ 1-----3---| 0-----2-----4| map(innerObs => innerObs.count()) --+--+---------| \ \ ---------2| ------------3| mergeAll --------------(3,2)| */
[RxJS] Split an RxJS Observable into groups with groupBy
原文：http://www.cnblogs.com/Answer1215/p/6213448.html