PureComponentExample-Parent.js

import React, { Component } from 'react';
import FirstChild from './FirstChild';
import SecondChild from './SecondChild';

export default class Parent extends Component {
  constructor(props, context) {
    super(props, context);
    this.state = {
      text: Math.random()
    };
  }
  
  componentDidMount() {
    setInterval(() => this.setState({ text: Math.random() }), 1000);
  }
  
  render() {
    return (
      <div>
        <FirstChild
          text={this.state.text}
        />  
        <SecondChild
          text="some random data"
        />
      </div>
    );
  }
}