empty

  • 语法:
public static empty(scheduler: Scheduler): Observable
  • 功能: 创建一个不发射任何值的Observable,它只会发射一个complate通知。

仅仅发射一个‘complate’,除此之外,不会发射其他值。

该操作符创建一个仅发射‘complete’的通知。通常用于和其他操作符一起组合使用。

eg:

//Emit the number 7, then complete.
var result = Rx.Observable.empty().startWith(7);
result.subscribe(x => console.log(x));
//Map and flatten only odd numbers to the sequence 'a', 'b', 'c
var interval = Rx.Observable.interval(1000);
var result = interval.mergeMap(x =>
  x % 2 === 1 ? Rx.Observable.of('a', 'b', 'c') : Rx.Observable.empty()
);
result.subscribe(x => console.log(x));

f-eg:

var source = Rx.Observable.empty();

var subscription = source.subscribe(
  x => console.log(`onNext: ${x}`),
  e => console.log(`onError: ${e}`),
  () => console.log('onCompleted'));

// => onCompleted

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