React Base Fiddle (JSX)

Starting point for creating JSFiddles with React. This uses React with Addons.

HTML

<script src="https://cdnjs.cloudflare.com/ajax/libs/babel-core/5.8.24/browser.js"></script>
<script src="https://npmcdn.com/react@latest/dist/react-with-addons.js"></script>
<script src="https://npmcdn.com/react-dom@latest/dist/react-dom.js"></script>
<script src="https://facebook.github.io/react/js/jsfiddle-integration-babel.js"></script>

<div id="container">
  <!-- This element's contents will be replaced with your component. -->
</div>

JavaScript 1.7

class HelloWidget extends React.Component {
    constructor(props) {
      super(props);
      this.names_holder = [];
      this.state = {
        name: []
      };
    }

    handleClick = () => { //error here
      let random = this.names_holder.concat(Math.ceil(Math.random() * 10) + 3);
      this.setState({
        name: random
      });
    }

    render() {
      return <div className = "widget" >
        < button onClick = {
          this.handleClick
        } > Random concat < /button> {
          JSON.stringify(this.state.name)
        } < /div>;
    }



    ReactDOM.render( < HelloWidget name = "World" / > ,
      document.getElementById('container')
    );
}