Egghead.com The Beginner's Guide To ReactJS Tutorial: Use Class Components With React

use_class_components_with_react_0.html

<script type="text/babel">
      class Counter extends React.Component {
        constructor(...args) {
          super(...args);
          this.state = { count: 0 }
        }
        render() {
          return (
            <button
              onClick={ () =>
                this.setState(({ count }) => ({
                  count: count + 1,
                }))}
            >
              { this.state.count }
            </button>
          )
        }
      }
      ReactDOM.render(
        <Counter />,
        document.getElementById('root')
      );
    </script>