How to add multiple middleware to Redux?

applyMiddleware takes each piece of middleware as a new argument (not an array). So just pass in each piece of middleware you'd like.

const createStoreWithMiddleware = applyMiddleware(ReduxThunk, logger)(createStore);

applyMiddleware should pass into createStore as the second parameter. applyMiddleware can have multiple middlewares as arguments.

const store = createStore(reducers, applyMiddleware(ReduxThunk, logger));

ReactDOM.render(
  <Provider store={store}>
    <App />
  </Provider>,
  document.querySelector('#app')
);

answer of andy's is good, but, consider your middlewares growing, below codes will be better:

const middlewares = [ReduxThunk, logger]
applyMiddleware(...middlewares)