CODE EXAMPLE FOR JAVASCRIPT

Pure Component In React

import React from 'react';    
import PropTypes from 'prop-types';  
  
class Main extends React.Component {    
    constructor(props) {  
      super(props);          
      this.state = {  
         city: "Alwar",  
      }  
   } 
   
   componentDidMount(){
       setInterval(()=>{
           this.setState(()=>{
               return { city: "Alwar"}
           })
       },2000)
   }
   render() {  
       console.log('Main Component render');  
      return (  
          <div>    
         <h2>    
            {this.state.title}   
         </h2>    
         <p>User Name: {this.props.name}</p>  
         <p>User Age: {this.props.age}</p>  
         </div>  
      );    
   }  
     
}    
Main.propTypes ={  
       name:PropTypes.string.isRequired,  
       age:PropTypes.number.isRequired  
   }  
  
Main.defaultProps = {  
  name: 'Pankaj Kumar Choudhary',  
  age: 24  
};  
    
export default Main;