角度：焦点不会多次触发

Question

const events = [
    'input',
    'focus'
];
const eventStreams = events.map((ev) =>
    Observable.fromEvent(this.inputElem.nativeElement, ev).map((event) => 
    event['target'].value).debounceTime(this.delay).distinctUntilChanged()
  );
const allEvents$ = Observable.merge(...eventStreams);

this.subscription = allEvents$.subscribe((input) => {
  this.showSuggestions = true;
  this.inputChange.emit(input);  
});

if (this.SuggestionsOverlayElem) {
  this.styleSuggestionOverlay();
}

onfocus 只能首次使用，但不会被触发 如果我多次关注。但是每当我 专注于文本输入。