Defining PropTypes for a component example.

MyComponentPropTypes.js

import PropTypes from 'prop-types'

export default class MyComponent extends React.Component {

  render() {
    // Render Something
  }
}

// You can declare that a prop is a specific JS type. 
MyComponent.propTypes = {
  text: PropTypes.string.isRequired,
  content: PropTypes.array.isRequired,
  onPress: PropTypes.func.isRequired,
  size: PropTypes.number.isRequired,
  styles: PropTypes.object.isRequired,
  isReady: PropTypes.bool.isRequired,
}