问Meta标记上渲染的Angular 4

EN

const routes: Routes = [
  { path: 'products/:slug', component: ProductComponent }
];

ngOnInit() {
    let currentSlug = this.route.snapshot.paramMap.get('slug');

    //Makes ajax call to server to get meta data
    this.MyMetaService.getMeta(currentSlug)
        .subscribe((metadata) = > {
          //Set the page title
          this.title.setTitle(metadata.title);

          this.meta.addTags([
            {name: 'keywords', content: metadata.keywords},
            {name: 'description', content: metadata.description}
        ])
      });
  }

ngAfterViewInit() {
    const title = $(document).find("title").text();
    console.log('page title is: ', title); //title is still not updated!
  }

setTimeout(() => {
    const title = $(document).find("title").text();
    console.log('page title is: ', title); //Got correct title here!
}, 200);