Typescript, Angular 2 - Parse Json to object in http

I have a file location.json, containing JSON string of the form:

{
  "locations": [
    {
      "id": 1,
      "places": [
        {
          "id": 1,
          "city": "A",
          "state": "AB"
        }
      ]
    }
}

I created classes of the form:

export class Location{
       constructor(public id: number,
        public places: Place[],
     }

export class Place {
        constructor(
        public id: number, 
        public city: string,
        public state: string
} 

How do I parse the JSON string to object? I did something like this:

...
export class DashboardComponent {

  locations: Locations[];

  constructor(private locationService:LocationService) {
    this.getLocations() 
  }

  getLocations(){
      this.locationService.get('assets/location.json')
      .subscribe(res => this.location = res);
  }