class SonComponent extends React.Component {
  handleValue(event) {
    this.props.handleValue(event.target.value)
  }
  
  render() {
    return (
      <div>
        <input type="text" placeholder="Please Input" onChange={this.handleValue.bind(this)} />
      </div>
    )
  }
}

class ParentComponent extends React.Component {
  handleValue(value) {
    console.log(value)
  }
  
  render() {
    return (
      <SonComponent handleValue={this.handleValue} />
    )
  }
}

ReactDOM.render(<ParentComponent />, document.getElementById("root"))