title: Angular clear textarea value in form, but form value should be present
body: <p>I'm using Reactive forms in angular I have an textarea and an add button , 
  when I enter some value in textarea and click on add button an link will be generated above the text area, after each value is added i want to clear the textarea ,but the value should be present in the form.</p>
  
  <pre><code>&lt;form [formGroup]="myForm"&gt;
  &lt;div *ngFor="let item of links"&gt;
  &lt;a href="{{ item.link }}" target="blank"&gt;{{ item.link }}&lt;/a&gt;
  &lt;/div&gt;
  &lt;div&gt;
  &lt;textarea formControlName="documentLink"&gt;&lt;/textarea&gt;
  &lt;button type="submit" (click)="addlink(myForm)"&gt;Add&lt;/button&gt;
  &lt;/div&gt;
  &lt;/form&gt;
  
  export class AppComponent {
  public documentLink: string[] ;
  public links = Array&lt;{ link: string }&gt;();
  public myForm: FormGroup = new FormGroup({
  documentLink: new FormControl()});
  public linkdata=[]
  addlink(data: any) {
  if(data.value.documentLink==''){
  alert("Please enter valid link");
  return;
  }
  else
  {
  this.links.push({ link: data.value.documentLink });
  for(let i=0;i&lt;this.links.length;i++){
  this.linkdata.push(this.links[i].link)
  }
  this.myForm.setValue({documentLink: this.linkdata})
  console.log(this.myForm.value)
  } 
  }
  </code></pre>