问如何在angular中触发datalist的点击事件

EN

<input
  #myDiv
  type="text"
  id="test"
  list="codes"
  [(ngModel)]="codeValue"
  (change)="saveCode($event)"
/>
<datalist id="codes">
  <option *ngFor="let c of codeList" [value]="c.name">{{c.name}}</option>
</datalist>
<span (click)="testfn()"> test<span></span></span>

  public codeValue: string;

  codeList = [
    { id: 1, name: "Angular 2+" },
    { id: 2, name: "Angular 4" },
    { id: 3, name: "Angular 5" },
    { id: 4, name: "Angular 6" },
    { id: 5, name: "Angular 7" }
  ];

  @ViewChild("myDiv") myDiv: ElementRef<HTMLElement>;

  constructor(private ref: ElementRef) {}

  public saveCode(e): void {
    let name = e.target.value;
    let list = this.codeList.filter(x => x.name === name)[0];
    console.log(list.id);
  }

  testfn() {
    debugger;
    console.log("test");
    let dummy = this.ref.nativeElement.querySelector("#test");
    dummy.click();
    dummy.dispatchEvent(new Event("click"));
    let el: HTMLElement = this.myDiv.nativeElement;
    el.click();
  }