title: how to set value on button click in react js?
body: <p>I want to change the state value on button click using react js.I am able to get click event .But the set value not updated why .I used this </p>
  
  <pre><code>btnClick(){
      alert('---')
    //  this.setState({data: 'nannsd'});
       this.state ={data: 'sds'};
    }
  </code></pre>
  
  <p>here is my code
  <a href="http://codepen.io/naveennsit/pen/MydPJM" rel="nofollow">http://codepen.io/naveennsit/pen/MydPJM</a></p>
  
  <pre><code>class App extends React.Component{
    constructor(){
       super();
      this.state ={data: 'test'};
    }
    btnClick(){
      alert('---')
    //  this.setState({data: 'nannsd'});
       this.state ={data: 'sds'};
    }
  
    render(){
      return &lt;div&gt;
        hello {this.state.data}
        &lt;button onClick={this.btnClick}&gt;click&lt;/button&gt;
      &lt;/div&gt;
    }
  
  }
  
  React.render(&lt;App/&gt;,document.getElementById('app'))
  </code></pre>