const a$ = Rx.Observable.interval(50).take(3);
const b$ = Rx.Observable.just('Boston');
const c$ = Rx.Observable.just('Colorado');

import combineLatestObj from 'rx-combine-latest-obj';

const state$ = combineLatestObj({a$, b$, c$});
// or const state$ = combineLatestObj({a: a$, b: b$, c: c$});

state$.subscribe(x => console.dir(x));
// {a: 0, b: 'Boston', c: 'Colorado'}
// {a: 1, b: 'Boston', c: 'Colorado'}
// {a: 2, b: 'Boston', c: 'Colorado'}

var stateAlt$ = Rx.Observable.combineLatest(
  a$, b$, c$, (a, b, c) => ({a, b, c})
);