Angular2 Rxjs键控如何连接字符

像这样输入

<input #term (keyup)="search()">

所以我试着

const obs$: Observable<KeyboardEvent> = Observable.fromEvent(this.getNativeElement(this.term), 'keyup');
    obs$
    .debounceTime(500)
    .map(ev => ev.key)
    .distinctUntilChanged()
    .scan((acc, one) => acc + one)
    .do(x => console.log(x))
    .subscribe(term => this.search(term));

除非你不使用退格,否则一切都很好

a
app.component.ts:49 av
app.component.ts:49 avf
app.component.ts:49 avfd
app.component.ts:49 avfdBackspace
app.component.ts:49 avfdBackspaced
app.component.ts:49 avfdBackspaceds
app.component.ts:49 avfdBackspacedsw
app.component.ts:49 avfdBackspacedswControl

那么,我可以使用什么来获得正确的输入?

更新

我可以这样做

term$ = new Subject<string>();
(input)=term$.next($event.target.value)

更新2(见@meligy的回复)

Observable.fromEvent<HTMLInputElement>(this.getNativeElement(this.term), 'keyup')
    .debounceTime(500)
    .map(ev => ev.target.value)
    .distinctUntilChanged()
    .do(termDebug => console.log(termDebug))
    .switchMap(term => this.service.search(term))
    .subscribe(result => this.items = result);