Why doesn't the promise work in Angular 2?

Question

JavaScript

method in service:

testpromise():any{
    console.log('json called');
    return new Promise(resolve => {
      this.http.get('assets/list.json').map((response) => {
        resolve(response.json());
      });
    });
  }

Call:

ngOnInit() {
    this.assignmentsService.testpromise().then(
      result => {
        alert("Fulfilled: " + result);
      },
      error => {
        alert("Rejected: " + error);
      }
    );

    this.assignments = this.assignmentsService.getAssignments()
      .slice(0, 5)
      .map(x => new AssignmentView(x));
  }

Answer 1

rxjs has a nice feature called .toPromise() do
and the method will return a promise to you, and you don’t need to turn around and pervert in anything)

Answer 2

Mb the problem is that it does not work with http, tk. from the code it looks like it's a stream from rxjs. To make it run, you need to subscribe to it instead of map.
Try

this.http.get('assets/list.json').subscribe(response => resolve(response.json()));