this.state is null ``` class Square extends React.Component { getzhi(){ console.log('1') } render(){ return( <div> <button onClick={()=> this.setState({value:'X'}) }>{this.state.value}</button> </div> ) } } ``` ``` class Square extends React.Component { constructor(props){ super(props); this.state = { value: null } } getzhi(){ console.log('1') } render(){ return( <div> <button onClick={()=> this.setState({value:'X'}) }>{this.state.value}</button> </div> ) } } ```