class App extends React.Component {

​

  constructor(props){

​

    super(props);

​

    this.state = { arr : [] , show : false }

  }

​

  handleChange = ()  => {

​

​

    var arrNew = [{ name: "hasan ", age: 645 }, { name: "hasan ", age: 64 }, { name: "hasan ", age: 6} ]; 

​

    //console.log("old state ----> ", this.state.arr)

    this.setState({

       arr: [...this.state.arr, ...arrNew],

      show : true

    })

​

    //console.log("new state ----> ",this.state.arr)

​

  }

​

​

  render() {

    return (

      <div className="App">

​

      <button onClick= { this.handleChange } > Get Data </button>

​

      <div id="show">

      { 

         this.state.show ? (this.state.arr.map((data, i)=> (

            <ul key={i}>

             <li> {data.name} </li>

             <li> {data.age} </li>

            </ul>

          ))) : null

      }

​

      </div>

​

      </div>

    );

  }

}

​

ReactDOM.render(

  <App/>, 

  document.querySelector('#root')

);