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JavaScript React Basics (retired) Stateful Components Creating a Component Class

Xiaoxuan Wang
Xiaoxuan Wang
4,590 Points

How to define propTypes in the component class if using ES6?

I coded the component class in the video in ES6:

class Counter extends React.Component {
  render() {
    return <div className="counter">
      <button className="counter-action decrement"> - </button>
      <div className="counter-score"> {this.props.score} </div>
      <button className="counter-action increment"> + </button>

Unlike the example which Jim define propTypes inside the component class, but how shall I do if using ES6 syntax?


2 Answers

Abraham Juliot
Abraham Juliot
47,353 Points

Per the propType npm and facebook docs, it's just the same as we had when using the functional component.

Counter.propTypes = {
    score: React.PropTypes.number.isRequired    

In React 15.5, PropTypes is extracted from the React object, and is its own separate package. This means you would need to install and import prop-types in your file. instead of using


you use


Here is an article on the topic: https://reactjs.org/blog/2017/04/07/react-v15.5.0.html#migrating-from-react.proptypes

Luis Lopez
Luis Lopez
1,288 Points
import React, {Component} from 'react';
import PropTypes from 'prop-types';

class Counter extends Component {
  static propTypes = {
      score: PropTypes.number.isRequired
  render() {
    return (
      <div className="player-score">
        <div className="counter">
          <button className="counter-action decrement ">-</button>
          <div className="counter-score">{this.props.score}</div>
          <button className="counter-action increment ">+</button>

This is how I wrote it using React v16 in my own editor utilizing create-react-app, I also had to npm install prop-types. Hope this helps anyone in a similar situation.