multiselect.component.ts

export class MultiselectComponent implements ControlValueAccessor {
  [...]

  private onChange = (_: Array<ListItem>) => { };
  private onTouch = () => { };

  @HostListener('document:click', ['$event.target'])
  public onClick(targetElement) {
    const clickedInside = this.multiselect.nativeElement.contains(targetElement);
    if (!clickedInside) {
      this.closeDropdown();
      this.onTouch();
    }
  }

  @HostListener('blur')
  public onTouched() {
    this.closeDropdown();
    this.onTouch();
  }

  writeValue(items: Array<ListItem>): void {
    this.selectedItems = items;
    this.onChange(this.selectedItems);
  }

  registerOnChange(fn: any): void {
    this.onChange = fn;
  }

  registerOnTouched(fn: any): void {
    this.onTouch = fn;
  }

  setDisabledState?(isDisabled: boolean): void {
    throw new Error('Method not implemented.');
  }

  [...]
}