freeCodeCamp/guide/english/certifications/front-end-libraries/redux/write-a-counter-with-redux/index.md

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title: Write a Counter with Redux
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# Write a Counter with Redux

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## Problem Explanation
The goal of this challenge is to apply all the concepts learned from previous Redux challenges and create a simple counter that will increment or decrement a state by 1. 


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## Hints

### Hint 1
The best way to solve this challenge is by reviewing previous redux lessons particularly the following:
- [Use const for Action Types](https://learn.freecodecamp.org/front-end-libraries/redux/use-const-for-action-types/)
- [Use a Switch Statement to Handle Multiple Actions](https://learn.freecodecamp.org/front-end-libraries/redux/use-a-switch-statement-to-handle-multiple-actions/)
- [Define an Action Creator](https://learn.freecodecamp.org/front-end-libraries/redux/define-an-action-creator/)
- [Handle an Action in the Store](https://learn.freecodecamp.org/front-end-libraries/redux/handle-an-action-in-the-store/)
- [Create a Redux Store](https://learn.freecodecamp.org/front-end-libraries/redux/create-a-redux-store)


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## Solutions

<details><summary>Solution 1 (Click to Show/Hide)</summary>

```javascript
const INCREMENT = "INCREMENT"; // define a constant for increment action types
const DECREMENT = "DECREMENT"; // define a constant for decrement action types

// define the counter reducer which will increment or decrement the state based on the action it receives
const counterReducer = (state = 0, action) => {
  switch (action.type) {
    case INCREMENT:
      return (state += 1);

    case DECREMENT:
      return (state -= 1);

    default:
      return state;
  }
};

// define an action creator for incrementing
const incAction = () => {
  return {
    type: INCREMENT
  };
};

// define an action creator for decrementing
const decAction = () => {
  return {
    type: DECREMENT
  };
};

// define the Redux store here, passing in your reducers
const store = Redux.createStore(counterReducer);
```
</details>