redux-wait

A helper to let you wait for redux actions to be processed in a universal app.

Installation

npm install redux-wait

Usage

1. Replace applyMiddleware with redux-await

- var applyMiddleware = require('redux').applyMiddleware;
+ var applyMiddleware = require('redux-wait');

This will add an extra method to your store called store.renderToString.

2. Ensure all middleware returns a promise (or runs synchronously)

If you're not using any custom middleware and you're not using redux-thunk, you can skip this step.

If you are writing asynchronous middleware, you need to make sure your middleware returns a promise that is only resolved once it has finished processing the action. redux-promise is a perfect example of how to do this.

If you are using redux-thunk, you can only use it synchronously, or it will break server rendering.

Good:

// action creator
function loadUser(login) {
  return (dispatch, getState) => {
    const user = getState().entities.users[login];
    if (user) {
      return null;
    }
 
    return dispatch(fetchUser(login));
  };
}

Bad:

// action creator
function loadUser(login) {
  return (dispatch, getState) => {
    const user = getState().entities.users[login];
    if (user) {
      return null;
    }
 
    $.getJson('/user/' + login, function (data) {
      // The server won't wait for this action :(
      dispatch({type: 'LOADED_USER', user: data});
    });
  };
}

3. Ensure that actions to load data are not fired if the data is alreay loading

Good:

componentWillMount() {
  if (!this.props.isLoading && !this.props.user) {
    this.props.dispatch(loadUser());
  }
}

Bad:

componentWillMount() {
  if (!this.props.user) {
    this.props.dispatch(loadUser());
  }
}

4. Render the page in your server

// N.B. `createStore` is the result of using redux-wait instead of Redux.applyMiddleware
let store = createStore();
let element = <Root history={new MemoryHistory([req.url])} store={store} />;
store.renderToString(React, element).done(function (html) {
  res.send(
    indexHtml.replace(
      '{{content}}',
      html
    ).replace(
      '{{state}}',
      stringify(store.getState())
    )
  );
}, next);

License

MIT