eslint-plugin-react: prop-types does not work with static propTypes

You can always use ES6 getters, so the class becomes

export default class Greeting extends React.Component {
  static get propTypes() {
    return {
       count: React.PropTypes.number.isRequired
    }
  }
  render () {
    return <h1>Hello, world! {this.props.count} greetings from me!</h1>;
  }
}

Actually there is a typo in your code, the static property declaration must be followed by a =, not a :.

The fixed class:

export default class Greeting extends React.Component {
  static propTypes = {
    count: React.PropTypes.number.isRequired
  }
  render () {
    return <h1>Hello, world! {this.props.count} greetings from me!</h1>;
  }
}

Babel don’t throw an error but do not export the property in the transpiled code neither, so it is like you did not had any declared propTypes. With Espree, the default ESLint parser, you’ll get an Unexpected token : error.

You can compare Babel output here http://babeljs.io/repl

Getters and setters are an ES5 feature, and ES6 doesn’t change their performance profile at all. https://bugzilla.mozilla.org/show_bug.cgi?id=626021 https://bugs.chromium.org/p/v8/issues/detail?id=1239 are two examples I found with brief googling. The maintainability part may be subjective but it’s a majority best practice in the JS community to avoid getters and setters, and always has been.

@ljharb Thanx for the links. I learned something new today. So I guess the best option here is to use Greeting.propTypes

Ran into this today while building a boilerplate using React 16 (Webpack 4, Babel 7) …

If the solution is declare propTypes outside of the class, then I have no issues with that solution.

import React, { Component } from 'react';
import PropTypes from 'prop-types';

export default class Taco extends Component {
    render() {
        return (
            <div>{this.props.taco.sauce}</div>
        );
    }
}

Taco.propTypes = {
    taco: PropTypes.shape({
        sauce: PropTypes.string
    })
};

Class properties are a Stage 0 proposal for ES7.

So, moving propTypes out of the class seems safer for now if you do not want to rely on an experimental feature.