how to use setstate
class App extends React.Component { state = { count: 0 } handleIncrement = () => { this.setState({ count: this.state.count + 1 }) } handleDecrement = () => { this.setState({ count: this.state.count - 1 }) } render() { return ( <div> <div> {this.state.count} </div> <button onClick={this.handleIncrement}>Increment by 1</button> <button onClick={this.handleDecrement}>Decrement by 1</button> </div> ) } }