Suck less at React (utilities #1): Switch Components

SwitchIf.jsx

import React from 'react'
import propTypes from 'prop-types'
import SwitchWhen from './SwitchWhen'

class SwitchIf extends React.PureComponent {
  static propTypes = {
    test: propTypes.any.isRequired,
    equals: propTypes.any,
    children: props => (
      React.Children
        .toArray(props.children)
        .some(Component => (
          ![SwitchIf, SwitchWhen].includes(Component.type)
        ))
        ? new Error('children must be an instance of SwitchWhen or SwitchIf')
        : null
    ),
  }
  static defaultProps = {
    children: null,
    equals: undefined,
  }
  render() {
    const { children, test } = this.props
    return React.Children
      .toArray(children)
      .find(Component => Component.props.equals === test) || null
  }
}

export default SwitchIf

SwitchWhen.jsx

import React from 'react'
import propTypes from 'prop-types'

class SwitchWhen extends React.Component {
  static propTypes = {
    equals: propTypes.any.isRequired,
    render: propTypes.node.isRequired,
  }
  render() {
    return this.props.render
  }
}

export default SwitchWhen