reduxfreeze.js

// this component freezes redux state for its children when `cold` is true
// after every render, it saves a snapshot of the last used redux state
// it also replacies the redux store with a 'proxy' store, which, when cold
// - no-ops all action dispatches
// - returns state from the snapshot
class Freeze extends Component<{ cold: boolean, children: Node }> {
  context: {
    store: Store,
  };
  static contextTypes = {
    store: x => null,
  };
  // our proxy store
  store = {
    getState: () => {
      if (this.props.cold) {
        return this.snapshot;
      }
      return this.context.store.getState();
    },
    dispatch: action => {
      if (!this.props.cold) {
        this.context.store.dispatch(action);
      }
    },
    subscribe: listener => {
      return (
        this.context.store.subscribe(() => {
          if (!this.props.cold) {
            listener();
          }
        })
      );
    },
    replaceReducer: next => {
      // should this be a no-op too?
      return this.context.store.replaceReducer(next);
    },
  };

  snapshot = this.context.store && this.context.store.getState();

  componentDidUpdate() {
    if (this.context.store && !this.props.cold) {
      this.snapshot = this.context.store.getState();
    }
  }

  render() {
    return <Provider store={this.store}>{this.props.children}</Provider>;
  }
}