contohUseState.js

export class ContohUseState extends React.Component {
  state = { count: 0 };
  render() {
    const { count } = this.state;
    return (
      <p>
        <button onClick={() => this.setState({ count: count - 1 })}>-</button>
        <b>{count}</b>
        <button onClick={() => this.setState({ count: count + 1 })}>+</button>
      </p>
    );
  }
}