Extending rxjs

extractMap.ts

import { Observable } from 'rxjs/Observable';

function extractMap<T>(this: Observable<T>): Observable<T> {
  return this.map(json => {
    const data = <any>json;
    return data.success ? data.result : Observable.throw('Response contained an unsuccessful status');
  });
}

Observable.prototype.extractMap = extractMap;

declare module 'rxjs/Observable' {
  interface Observable<T> {
    extractMap: typeof extractMap;
  }
}