如何将jQuery $(document).scrolltop()代码转换为react js

Question

如何将jQuery卷轴代码转换为reactjs？

if($(".app-wizard-header").length > 0) {            
  if ($(document).scrollTop() > 50) {                  
      this.setState({Headerbg:'app-wizard-header'})          
  } else {                 
      this.setState({Headerbg:'app-wizard-header no-bg'})          
  }
}

Answer 1

答案：

import ReactDOM from 'react-dom';
var node = ReactDOM.findDOMNode(this.refs.Headerbg);            
if (node){
  if (window.scrollY > 50) {                  
      this.setState({...});          
  } else {                 
      this.setState({...});          
  }
}