Solution: Practice with Directives

Explanation

The only thing we need to change is the directive’s selector. We can match all elements with the class name header as follows:

@Directive({
  selector: '.header'
})
export class BoldDirective {

  constructor(el: ElementRef) {
    el.nativeElement.style.fontWeight = 'bold';
  }
}

Solution

Here’s an example of what the solution for this task may look like: