Typescript - type 'false' is not assignable to type 'true' [closed]

Question

I am learning angular 2, and in this example where I set the variable for isLoading to true, and then change it to false, once I fetch the data I need, I get the error:

Typescript - type 'false' is not assignable to type 'true'

This is the code:

export class AppComponent implements OnInit {
    isLoading: true;

    constructor(private _articleService: ArticleService, private _postService: PostService){}

    ngOnInit(){
      this.articles = this._articleService.getArticles();
      this._postService.getPosts()
        .subscribe(posts => {
          this.isLoading = false;
          console.log(posts[0].title);
        });
    }

Answer 1

Not required to define the type of variable at a time, but you should set to find bugs during development. In addition editor before know to complete the code thus he knows the type of the variable.

export class AppComponent implements OnInit {
isLoading : boolean =  true;

constructor(private _articleService: ArticleService, private _postService: PostService){}

ngOnInit(){
  this.articles = this._articleService.getArticles();
  this._postService.getPosts()
    .subscribe(posts => {
      this.isLoading = false;
      console.log(posts[0].title);
    });
}

Answer 2

isLoading: true; means that the only value you can assign to isLoading is the value true. You want isLoading: boolean.

Answer 3

Based on suggestions from comments and the answer from @Louis, this was the right syntax to fix it:

isLoading: boolean = true;