rxjs - 什么触发了 combineLatest？

Question

我有一些观察结果。我需要知道哪个触发了订阅。

Observable.combineLatest(
      this.tournamentsService.getUpcoming(),
      this.favoriteService.getFavoriteTournaments(),
      this.teamsService.getTeamRanking(),
(tournament, favorite, team) => {
//what triggered combinelatest to run?
}).subscribe()

Answer 1

实现这一点的一种非常干净和“rx”的方式是使用时间戳运算符 http://reactivex.io/documentation/operators/timestamp.html

示例代码

sourceObservable
  .pipe(
    timestamp(),  // wraps the source items in object with timestamp of emit
    combineLatest( otherObservable.pipe( timestamp() ), function( source, other ) {

      if( source.timestamp > other.timestamp ) {

        // source emitted and triggered combineLatest
        return source.value;
      }
      else {

        // other emitted and triggered combineLatest
        return other.value;
      }

    } ),
  )

如果 combineLatest() 中涉及两个以上的可观察量按时间戳对它们进行排序将能够检测哪个触发了 combineLatest() .