Set focus on <input> element

Question

I am working a front-end application with Angular 5, and I need to have a search box hidden, but on click of a button, the search box should be displayed and focused.

I have tried a few ways found on StackOverflow with directive or so, but can't succeed.

Here is the sample code:

@Component({
   selector: 'my-app',
   template: `
    <div>
    <h2>Hello</h2>
    </div>
    <button (click) ="showSearch()">Show Search</button>
    <p></p>
    <form>
      <div >
        <input *ngIf="show" #search type="text"  />            
      </div>
    </form>
    `,
  })
  export class App implements AfterViewInit {
  @ViewChild('search') searchElement: ElementRef;

  show: false;
  name:string;
  constructor() {    
  }

  showSearch(){
    this.show = !this.show;    
    this.searchElement.nativeElement.focus();
    alert("focus");
  }

  ngAfterViewInit() {
    this.firstNameElement.nativeElement.focus();
  }

The search box is not set to focus.

How can I do that?

Answer 1

Edit 2022:
Read a more modern way with @Cichy's answer below

---

Modify the show search method like this

showSearch(){
  this.show = !this.show;  
  setTimeout(()=>{ // this will make the execution after the above boolean has changed
    this.searchElement.nativeElement.focus();
  },0);  
}