重置在dom级ng-multiselect-下拉菜单中不起作用

Question

我在我的angular 7项目中使用ng-multiselect-dropdown。我想重置下拉列表的值，所以我使用下面的方法，但只清除了变量中存储的值； dom值未在我的模板中清除。我也需要验证。请帮助我。

resetSelection() {
  this.selectedTestCompounds = [];        
}

<ng-multiselect-dropdown  
  id="testSample"
  [placeholder]="'select'"
  [data]="sampleList"                                                 
  [(ngModel)]="selectedTestCompounds"                                 
  [settings]="dropdownSettingsTestCompound"                           
  (onSelect)="onItemSelectTestCompound($event)"                       
  (onSelectAll)="onSelectAllTestCompound($event)"
  >
</ng-multiselect-dropdown>
<button (click)="resetSelection()" >clear</button>