ChildComponent.js

import React, { Component } from 'react';
import { string, func } from 'prop-types';
import './child-component.css';

export default class ChildComponent extends Component {
   static propTypes = {
       label: string,
      onSubmit: func.isRequired
   };

   static defaultProps = {
      label: “I’m your son”
   };

   constructor (props) {
      super(props);
   };

   onClick = () => (onSubmit(this.props.label));

   render () {
      const { onSubmit, label} = this.props;
      return(
        <div className="container">
          <Button onClick={onClick()}>{label}</Button>
        </div>
      );
   };
};