Edit in JSFiddle

var Hello = React.createClass({
    renderCount: 0,
    getInitialState: function() {
        return {value: 0};
    },
    countUp: function() {
        this.setState({value : this.state.value + 1});
    },
    render: function() {
        // count how many times 'render' was called
        this.renderCount += 1;
        return (
            <div>
            <div>Count: {this.state.value}</div>
            <div>Render: {this.renderCount}</div>
            <button onClick={this.countUp}>Count Up</button>
            </div>
        );
    }
});
 
React.render(<Hello />, document.body);

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