Introducing the Meta service

Angular has introduced a new service called the Meta service that simplifies updating or getting the meta tags:

@Component({   
  selector: 'book-list',   
  template: `<h1>Book   List</h1>`   
})   
export class BookComponent {   
  constructor(meta: Meta) {   
    meta.addTag({ name: 'author',   content: 'Rajesh Gunasundaram' });   
  }   
}   

New form validators

New validator combines the existing validators such as required, minLength, maxLength, email, and pattern. Also, a new directive, compareWith, is introduced to compare options from a select control, as shown:

<select [compareWith]="byId"   [(ngModel)]="selectedBook">   
   <option *ngFor="let book of   books" [ngValue]="book">{{book.title}}</option>   
</select>   
byId(p1: BookModel, p2:   BookModel) {   
   return p1.id === p2.id;   
}   

Introducing ParamMap in router

Angular has introduced a new interface, ParamMap, to map the parameters in a URL. We can use paramMap...