> For the complete documentation index, see [llms.txt](https://react-observatory.js.org/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://react-observatory.js.org/dynamic-injection/reducers.md).

# Reducers

This chapter covers the basic setup for Dynamic Reducer Injection.

Please note that reducers are not removed from Store when Component is unmounted.

## Global Reducer Setup

First, we need to create a function that will allow us to inject new reducers dynamically.

In this example, the `counter` reducer will be available on every page.

```javascript
import { composeReducerCreator } from '@react-observatory/inject-reducer'

const counter = (state = 0, action) => {
  return state + 1;
}

export default composeReducerCreator({
  counter
})
```

## Store Configuration

After that, we need to enhance the store with applyAsyncReducers.

It needs the `reducerCreator` to replace the old reducer with an updated one when we inject new reducers dynamically.

```javascript
import { createStore } from 'redux'
import { applyAsyncReducers } from '@react-observatory/inject-reduers'
import reducerCreator from './reducers'

const store = createStore(
  reducerCreator(),
  initialState,
  applyAsyncReducers(reducerCreator)
);
```

## Dynamic Reducer Injection inside the Components

Now we can start injecting reducers dynamically, the reducer for `TaskList` component will be loaded along with React Component.

```javascript
import { injectReducer } from '@react-observatory/inject-reducer'
import taskListReducer from './reducers'
import TaskList from './TaskList'

const withReducer = injectReducer('taskList', taskListReducer)

export default withReducer(TaskList)
```


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