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                <div id="app"></div>


                html, body {
  height: 100%;



Expandable component receives Header and Content as COMPONENT PROPS *o* (known as Component Injection)

 - Very obvious in render method that Expandable is wrapping this CustomExpandable component
 - Looks most "composable"
 - Should work very well with component prop types
 - Fairly nice namespacing
 - Enforces structure at the Expandable level, rather than the custom implementation

 - Maybe not as customisable? ie: if I want Content to render before Header, I can't. NOTE: could be mitigated with a renderProp ;)
 - You have to write out separate components for each prop (is this even a con?)

Read more: 
- Intro to this concept


class Expandable extends React.PureComponent {
  constructor(props) {
    this.state = {
      isOpen: false
  toggleOpen = () => {
    this.setState({ isOpen: !this.state.isOpen })
  render() {
    const { isOpen } = this.state
    const { 
    } = this.props
    const propsForInjectedComponents = {
      isOpen: isOpen,
      toggleOpen: this.toggleOpen,
    // TODO: maybe check for a props.render() here, if it exists, render that instead!

    return (
        <button onClick={this.toggleOpen}>
          <Header {...propsForInjectedComponents} />
        {isOpen && <Content {...propsForInjectedComponents} />}

class CustomExpandable extends React.Component {
  ExpandableHeader = (isOpen, toggleOpen) => (
    <span>Click me</span>
  // Pass isOpen and toggleOpen if needed
  ExpandableContent = (isOpen, toggleOpen) => (
  render() {
    return (

/** ==================================================================================== **/

class App extends React.Component {
  render() {
    return (
      <CustomExpandable />

  <App />