为什么这个throwError没有被catchError捕获？

Question

我正在尝试创建一个管道运算符并在不满足特定条件时抛出。但是我无法抛出并捕获错误。

这是我的管道：

// My custom pipeable
export function waitFor<T>(thisToComplete$: Observable<any>) {
  return (beforeRunningThis$: Observable<T>) => {
    return new Observable<T>(observer =>
      thisToComplete$.pipe(first()).subscribe(x => {
        if (x !== 'Success') {
          console.log('Non success result encountered');
          return throwError('Rando IO Error');
        }
        return beforeRunningThis$.subscribe(observer);
      })
    );
  }
}

消费代码：

const preReq$ = timer(1000);
const dataReq$ = getData();

try {
  dataReq$
    .pipe(waitFor(preReq$), catchError(x => {
      console.log('Code here reached');
      return of('Error was handled either here')
    }))
    .subscribe(x => console.log(`I have result ${x.toString()}`));
} catch (e) {
  console.log('Error was handled here');
}

None 但是上面的控制台日志。

这是一个stackblitz

Answer 1

由于您使用的是 Observable 结构 observer.error 就是你的投掷方式

    if (x !== 'Success') {
      console.log('Non success result encountered');
      observer.error('Rando IO Error');
    }

Answer 2

您需要删除管道运算符中的错误处理。基本上你在那里消费错误：

dataReq$
    .pipe(waitFor(preReq$))
    .subscribe(x => { 
      console.log(`I have result ${x.toString()}`);
    }, error => {
       console.log('Code here reached');
       // handle error
    });

为什么这个throwError没有被catchError捕获？

Why isn't this throwError being caught in catchError?

error-handling

rxjs

angular

rxjs-pipeable-operators