react组件的注册形式

组件的注册形式：
1.采用函数直接抛出jsx语法的方式
import React from "react";
import ReactDom from "react-dom";
let renderFn = () => {
const app = (

<h1>
  hello,world!
</h1>

);
return element
}

ReactDom.render(app, document.getElementById('app'));

2.采用createClass的方式开发(现已去掉)
import React from "react";
import ReactDom from "react-dom";
let app = React.createClass({

render(){
    return <div>hello,world!</div>
}

})
ReactDom.render(app, document.getElementById('app'));

3.采用es6的class类的方式
import React, {Component} from "react";
class App extends Component{

constructor(props) {
    super(props)
}
render(){
    return <div>react</div>
}

}
//main.js
import App from "./components/app.jsx";
ReactDom.render(<App/>, document.getElementById('app'));