Error: In Typescript, it is not possible to assign the type 'false' to type 'true'

Currently, I am exploring Angular 2 and encountered a situation where I set the variable isLoading to true initially, and then switch it to false after fetching required data. However, upon executing this process, I encountered the following error message:

In TypeScript - 'false' type cannot be assigned to 'true'

Here is the snippet of code causing the issue:

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

There is no need to specify the variable type initially, but it is important for detecting bugs during development. The editor can assist in completing the code which helps determine the variable type.

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

When <code>isLoading: true;, it restricts the value of isLoading to only be true. To allow for any boolean value, use isLoading: boolean.

Answer №3

After receiving feedback from various sources including @Louis, the following syntax was determined to be the correct solution:

isDataLoading: boolean = true;

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