createStore(reducer, [preloadedState], [enhancer])

Arguments

• (Function): A that returns the next state tree, given the current state tree and an to handle.

• [preloadedState] (any): The initial state. You may optionally specify it to hydrate the state from the server in universal apps, or to restore a previously serialized user session. If you produced reducer with combineReducers, this must be a plain object with the same shape as the keys passed to it. Otherwise, you are free to pass anything that your reducer can understand.

Returns

(Store): An object that holds the complete state of your app. The only way to change its state is by . You may also subscribe to the changes to its state to update the UI.

Example

Tips

• If your state is a plain object, make sure you never mutate it! For example, instead of returning something like Object.assign(state, newData) from your reducers, return . This way you don't override the previous state. You can also write return { …state, …newData } if you enable the .

• For universal apps that run on the server, create a store instance with every request so that they are isolated. Dispatch a few data fetching actions to a store instance and wait for them to complete before rendering the app on the server.

• To apply multiple store enhancers, you may use compose().