import React, {Component} from 'react';

​

class ButtonCounter extends Component {

  constructor() {

    super()

    // initial state has count set at 0

    this.state = {

      count: 0

    }

  }

​

  handleClick = () => {

    // when handleClick is called, newCount is set to whatever this.state.count is plus 1 PRIOR to calling this.setState

    let newCount = this.state.count + 1

    this.setState({

      count: newCount

    })

  }

​

  render() {

    return (

      <div>

        <h1>{this.state.count}</h1>

        <button onClick={this.handleClick}>Click Me</button>

      </div>

    )

  }

}

​

export default ButtonCounter

​

 // React change state

this.setState({state to change:value});

// Correct

this.setState(function(state, props) {

  return {

    counter: state.counter + props.increment

  };

});

  const [a, b] = React.useState(['hi','world']);

  const dup = [...a]; //won't work without spread operator

  b(dup);

You have to use setState() for updating state in React

{

  hasBeenClicked: false,

  currentTheme: 'blue',

}

​

setState({

    hasBeenClicked: true

});

​

 const [x, setX] = useState({y:"yyyyyy"}); 

function a()

{

setX({y:"######"}) 

}

...

​

  return(

​

<View style={styles.container}>

 <Button onPress={()=>

a() 

}  ref={inputEls} id={x} title={x.y}/>

 <Text>{x.y} </Text>

 </View>   

)