title: ReactJS: State is not changing
body: <pre><code>class Checkbox extends React.Component{
    constructor(props) {
      super(props);
      this.state = {
        checked: true
      }
    }
    changeClick()  {
      this.setState({checked: !this.state.checked})
    }
    render() {
      var chk;
      if(this.state.checked){
        chk='Checked';
      }else{
        chk='Unchecked'
      }
      return (
         &lt;div&gt;
           &lt;h2&gt;Checkbox is {chk}&lt;/h2&gt;
           &lt;input type='checkbox' onChange={this.changeClick} defaultChecked=
           {this.state.checked}/&gt;
        &lt;/div&gt;
    )
    }
  }
  ReactDOM.render(
    &lt;Checkbox /&gt;,
    document.getElementById("root")
  );
  </code></pre>
  
  <p>I'm new to React and trying to learn ES2015 too, can somebody help me with this, why State is not changing in this snippet.</p>
  
  <p>Any help would be appreciated thank you :)</p>