export class PostService {

posts = [
        {
          title: "Post 1",
          content: "bla bla bla",
          loveIts: 0,
          created_at: new Date,
        },
        {
          title: "Post 2",
          content: "bla bla bla",
          loveIts: 0,
          created_at: new Date,
        },
        {
          title: "Post 3",
          content: "bla bla bla",
          loveIts: 0,
          created_at: new Date,
        },
    ];

getPosts() {
    return this.posts;
}

setLoveItsToDefault() {
    for (let post of this.posts) {
        post.loveIts = 0;
    }
}

initializeLovesPost(i: number) {
    this.posts[i].loveIts = 0;
}
}

export class AppComponent {

@Input() posts : Post[];

constructor(private postService: PostService) {
}

ngOnInit() {
    this.posts = this.postService.getPosts();
}

onInitializeLoves() {
    if (confirm('Are you sure to initialize all loves of all posts to 0 ?')) {
        this.postService.setLoveItsToDefault();
    } else {
        return null;
    }
}
}

<button class="btn btn-primary" (click)="onInitializeLoves()">Initialize loves to 0</button>