Class Properties.js

export default class MyContainer extends Component {
  classPropertyA = 'something'
  classPropertyB = 123

  state = {
    stateItemA: undefined,
    stateItemB: 'default string'
  }
  
  someMethod = () => {
    // ...
  }
  
  anotherMethod = () => {
    // ...
  }
  
  render () {
    return (
      <SomeComponent />
    )
  }