React—条件渲染不同的组件

import React from 'react';
import ReactDom from 'react-dom';

class UserGreeting extends React.Component {
    render () {
        return (
欢迎回来！
)
    }
}
class GuestGreeting extends React.Component {
    render () {
        return (
请先注册！
)
    }
}
class Greeting extends React.Component {
    render () {
        if (this.props.isLogin == false) {
            return (
                
            )
        } else {
            return (
                
            )
        }
    }
}

ReactDom.render(
    

        
    
,
    document.getElementById('root')
)