Epic example with TypeScript, Redux, RxJS 6

unicorn.epic.ts

import { ofType } from 'redux-observable';
import { of } from 'rxjs';
import { catchError, flatMap, map, mergeMap } from 'rxjs/operators';
import UnicornActions from './unicorn.action';
import UnicornApiService from './unicorn.api.service';

export default class UnicornEpics {
  public static getUnicorn = (actions$: any) =>
    actions$.pipe(
      ofType(UnicornActions.Types.GET_UNICORN),
      mergeMap((action: any) =>
        UnicornApiService.getUnicorn(action.id)
          .pipe(
            map((res: any) => UnicornActions.done(res, UnicornActions.Types.GET_UNICORN)),
            catchError((error: any) => of(UnicornActions.error(error, UnicornActions.Types.GET_UNICORN)))
          )
      )
    );

  public static likeUnicorn = (actions$: any) =>
    actions$.pipe(
      ofType(UnicornActions.Types.LIKE_UNICORN),
      mergeMap((action: any) =>
        UnicornApiService.likeUnicorn(action.id)
          .pipe(
            flatMap((res: any) => of(
              UnicornActions.done(res, UnicornActions.Types.LIKE_UNICORN),
              UnicornActions.updateUnicorn(res.data.id, {color: 'rainbow'}),
            )),
            catchError((error: any) => of(UnicornActions.error(error, UnicornActions.Types.LIKE_UNICORN)))
          )
      )
    );

  public static updateUnicorn = (actions$: any) =>
    actions$.pipe(
      ofType(UnicornActions.Types.UPDATE_UNICORN),
      mergeMap((action: any) =>
        UnicornApiService.updateUnicorn(action.id, action.data)
          .pipe(
            map((res: any) => UnicornActions.done(res, UnicornActions.Types.UPDATE_UNICORN)),
            catchError((error: any) => of(UnicornActions.error(error, UnicornActions.Types.UPDATE_UNICORN)))
          )
      )
    );
}