React pass value from CHILD => Parent

index.js

import React,{Component} from 'react'
import logo from './logo.svg';
import Contact from './Contacts'
class App extends React.Component {
  
  //Pass the callback in the props 
constructor(props){
  super(props)
  this.state = {
    contacts : [
        {name : 'dev', country : 'india'},
        {name : 'Ram', country : 'india'},
        {name : 'charan', country : 'india'},
    ]
}
}

getValueFromContacts(data){
  console.log('getValue from contacts================' + data)
}

render() {
  return (
    <div className="App">
      <header className="App-header">
        <p>
          Learn React
        </p>
        <Contact contacts={this.state.contacts}  cb = {this.getValueFromContacts} />
      </header>
    </div>
  );
}

}

export default App;


class Contacts extends Component{

    render(){
        const {contacts} = this.props;
        console.log('contats', contacts)
  
        setTimeout(()=>{
            this.props.cb('12345.............');
        }, 5000)
        return (
            <div className='contact'>
                ozzx
            </div>
        )
    }
}

export default Contacts