import { Injectable } from '@angular/core';
import { Http, URLSearchParams, Response, RequestOptions, Headers } from '@angular/http';
import 'rxjs/RX';
import 'rxjs/add/operator/map';
@Injectable()
export class Service {
    apiRoot: string = 'https://jsonplaceholder.typicode.com/comments?'
    postId = 1;
    data;
    constructor(private _http: Http) {
        this._http.get(this.apiRoot).subscribe((data) => {
            this.data = data.json();
        });
    }
    init() {
        return this.data;
    }

}

import { Component, OnInit } from '@angular/core'; import { InfiniteService } from './infinite.service'; //import all rxjs/Rx opeartor  import 'rxjs/add/operator/map';

@Component({
    selector: 'app-root',
    templateUrl: './app.component.html',
    styleUrls: ['./app.component.css'] }) export class AppComponent implements OnInit {
    data;
    constructor(private _infinteService: InfiniteService) {
        this.data = this._infinteService.init();
        console.log(this.data);
    }

    GetPosition($event) {
        if ($event == 'Bottom') {
            console.log($event);
        }
        else {
            console.log($event);
        }
    }
    ngOnInit() {


    }

}

getData(): Observable<any> {
 return this._http.get(this.apiRoot)
}

this._infinteService.getData().subscribe(
 data => console.log(data)
)

//Subscribe your service in init() function and than call in your component

import { Injectable } from '@angular/core';
    import { Http, URLSearchParams,Response, RequestOptions, Headers} from
    @angular/http';
    import 'rxjs/RX';
    import 'rxjs/add/operator/map';
    @Injectable()
    export class Service {
     apiRoot:string='https://jsonplaceholder.typicode.com/comments?
     postId=1';
     data;
     constructor(private _http:Http) {
         this.init();
      }
      init(){
      this._http.get(this.apiRoot).subscribe((data)=>{
         this.data= data.json();
      });
     return this.data;
      }

      }