利用javascript scrolleventListener并计算窗口滚动高度，以触发异步调用。

请在构造函数中绑定必要的方法并定义状态。这是代码

componentDidMount(){
  if(this.state.newData.length === 0){
    window.addEventListener('scroll', this.handleOnScroll);
    this.doQuery(1).then(res=>
      this.setState({
       newData: this.state.newData.slice().concat(res),
      requestSent: false
    }))
  }
}

componentWillUnmount() {
  window.removeEventListener('scroll', this.handleOnScroll);
}

handleOnScroll(){
  var scrollTop = (document.documentElement && document.documentElement.scrollTop) || document.body.scrollTop;
  var scrollHeight = (document.documentElement && document.documentElement.scrollHeight) || document.body.scrollHeight;
  var clientHeight = document.documentElement.clientHeight || window.innerHeight;
  var scrolledToBottom = Math.ceil(scrollTop + clientHeight) >= scrollHeight;
  if (scrolledToBottom) {
    this.setState({
      scrollCounter: this.state.scrollCounter + Math.floor(scrolledToBottom)
    },()=>{
            if(this.state.scrollCounter<4){
      this.doQuery(this.state.scrollCounter).then(res=>
      (res===BUSY)
        ? false
        : this.setState({
            newData: this.state.newData.slice().concat(res)
          })
        )
        .catch(err=>this.setState({requestSent: false}))
        this.setState({requestSent: true});
    }else{
      return true
    }
 })
  }
}