TypeScript 2.x By Example

Logic for HTTP call

Now, we can use the _http object to make a web service call. We will create a function, getBoardsWithPromises where we will make a GET call to our JSON file and return the promise to the Homepage component.

The following is our code for the function:

getBoardsWithPromises(): Promise<Board[]> {        if(this.Boards == undefined){        return this._http.get(this._boardUrl).toPromise()            .then((response: Response) => {                this.Boards = <Board[]>response.json();                return <Board[]> response.json()   ;       } );                  }        else {            return Promise.resolve(this.Boards);        }    }

Let's go through each line of the function to understand the implementation:

• On the first line, we have the function name with the return type of the function. As we know that ...