Reactjs async rendering of components

The basic example of async rendering of components is below:

import React                from 'react';
import ReactDOM             from 'react-dom';        
import PropTypes            from 'prop-types';

export default class YourComponent extends React.PureComponent {
    constructor(props){
        super(props);
        this.state = {
            data: null
        }       
    }

    componentDidMount(){
        const data = {
                optPost: 'userToStat01',
                message: 'We make a research of fetch'
            };
        const endpoint = 'http://example.com/api/phpGetPost.php';       
        const setState = this.setState.bind(this);      
        fetch(endpoint, {
            method: 'POST',
            body: JSON.stringify(data)
        })
        .then((resp) => resp.json())
        .then(function(response) {
            setState({data: response.message});
        });
    }

    render(){
        return (<div>
            {this.state.data === null ? 
                <div>Loading</div>
            :
                <div>{this.state.data}</div>
            }
        </div>);
    }
}

There are two ways to handle this, and which you choose depends on which component should own the data and the loading state.

  1. Move the Ajax request into the parent and conditionally render the component:

    var Parent = React.createClass({
      getInitialState: function() {
        return { data: null };
      },
    
      componentDidMount: function() {
        $.get('http://foobar.io/api/v1/listings/categories/').done(function(data) {
          this.setState({data: data});
        }.bind(this));
      },
    
      render: function() {
        if (this.state.data) {
          return <CategoriesSetup data={this.state.data} />;
        }
    
        return <div>Loading...</div>;
      }
    });
    
  2. Keep the Ajax request in the component and render something else conditionally while it's loading:

    var CategoriesSetup = React.createClass({
      getInitialState: function() {
        return { data: null };
      },
    
      componentDidMount: function() {
        $.get('http://foobar.io/api/v1/listings/categories/').done(function(data) {
          this.setState({data: data});
        }.bind(this));
      },
    
      render: function() {
        if (this.state.data) {
          return <Input type="select">{this.state.data.map(this.renderRow)}</Input>;
        }
    
        return <div>Loading...</div>;
      },
    
      renderRow: function(row) {
        return <OptionRow obj={row} />;
      }
    });