app.js

TodoList.mapStateToProps = state =>
  ({ todos: getVisibleTodos(state.todos, state.visibilityFilter) })

TodoList.mapDispatchToProps = dispatch =>
  ({ onTodoClick: id => dispatch(toggleTodo(id)) })

wire(TodoList)

wire.js

function wire(type) {
  const WrappedComponent = type;

  class FinalComponent extends WrappedComponent {
    componentDidMount() {
      if (WrappedComponent.prototype.componentDidMount) {
        super.componentDidMount();
      }
      this[UNSUBSCRIBE] = this.context.store.subscribe(this[HANDLE_CHANGE]);
      this[HANDLE_CHANGE]();
    }

    componentWillUnmount() {
      if (WrappedComponent.prototype.componentWillUnmount) {
        super.componentWillUnmount();
      }
      this[UNSUBSCRIBE]();
    }

    [HANDLE_CHANGE] = () => {
      const { mapStateToProps, mapDispatchToProps } = type;
      const state = this.context.store.getState();
      const stateProps = mapStateToProps ?
        mapStateToProps(state, this.props) : undefined;
      const dispatchProps = mapDispatchToProps ?
        mapDispatchToProps(this.context.store.dispatch, this.props) : undefined;

      setProps(this, { ...stateProps, ...dispatchProps });
    }
  }

  // Store a reference to the connected component so we can create an element of it instead of the
  // original type in createElement().
  Type[COMPONENT] = FinalComponent;
  
  return FinalComponent;
 }