let obs = [];

​

let foo = Rx.Observable.create(function (observer) {

  obs.push(observer);

});

​

function trigger(sth){

//   console.log('trigger fn');

  obs.forEach(ob => ob.next(sth));

}

​

foo.subscribe(function (x) {

  console.log(`a:${x}`);

});

foo.subscribe(function (y) {

  console.log(`b:${y}`);

});

​

trigger(1);

trigger(2);

trigger(3);

trigger(4);