在前一个获得第一组数据之后合并一个新的Rx.Observable

Question

我正在使用从Json请求收到的数据创建无限滚动表。 问题是我需要在promise的第一个响应之后添加scroll observable。

    //Set Observables
var column = this.refs.column;
var columnScrollStream = Rx.Observable.fromEvent(column, 'scroll').filter(function () {
  return (column.scrollHeight - column.scrollTop == columnHeight);
});

var refreshTimeStream = Rx.Observable.timer(0, 30000);

var columnScrollSubscription = columnScrollStream.subscribe(function (scroll) {
  paginationNo += 10;
});

//Merge Observables
var requestStream = Rx.Observable
  .merge(refreshTimeStream, columnScrollStream)
  .map(function() {
      return url+'/0/'+paginationNo;
  };

// Use Observables
var responseStream = requestStream
  .throttle(400).flatMapLatest(function(requestUrl) {
    return Rx.Observable.fromPromise(jQuery.getJSON(requestUrl));
  });

//Use result   
this.subscription = responseStream.subscribe(function(result) {
  /* use result here*/
  /* !!! Place where the scoll Observable should be, because the column ref gets created only after the result is delivered */