what is render method in react code example

Example 1: lifecycles if reactjs

class Clock extends React.Component {
  constructor(props) {
    super(props);
    this.state = {date: new Date()};
  }

  componentDidMount() {  }
  componentWillUnmount() {  }
  render() {
    return (
      <div>
        <h1>Hello, world!</h1>
        <h2>It is {this.state.date.toLocaleTimeString()}.</h2>
      </div>
    );
  }
}

Example 2: react lifecycle hooks

class Content extends React.Component {
  // ...
  componentWillMount() {
    this.setState({ activities: data });
  }
  // ...
}

Example 3: ReactDOM.render()

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