React render() method

The render() format of the method is as follows:

ReactDOM.render(element, container[, callback])

render() method is used in the supplied container parameters container render a React element in the element .

render() method returns a reference to the component (or for stateless components null ).

If the React element is already in the container , which will update it and change the DOM only if necessary to map the latest React elements.

If an optional callback function is provided callback the callback willbe performed after the component is rendered or updated

The following examples are in use render() the method is in id="root" render React elements in the container of Header :

classHeaderextendsReact.Component{render(){return(<h1>Rookie Tutorial -
Learning is not only about technology, but also about dreams！</h1>);}}ReactDOM.render(<Header/>,document.getElementById('root'));