React componentDidMount() method

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

componentDidMount()

componentDidMount() method is called immediately after the component is mounted (inserted into the DOM tree).

Initialization that depends on the DOM node should be placed in the componentDidMount() in the method.

The following example outputs first runoob and then use the componentDidMount() method is set to output after the component is mounted google :

classHeaderextendsReact.Component{constructor(props){super(props);this.state={favoritesite:"runoob"};}componentDidMount(){setTimeout(()=>{this.setState({favoritesite:"google"})},1000)}render(){return(<h1>My favorite website is{this.state.favoritesite}</h1>);}}ReactDOM.render(<Header/>,document.getElementById('root'));