---
id: 5a24c314108439a4d4036157
title: Write a Counter with Redux
challengeType: 6
isRequired: false
videoUrl: ''
localeTitle: 用Redux写一个计数器
---
## Description
现在您已经了解了Redux的所有核心原则！您已经了解了如何创建操作和操作创建器，创建Redux存储，针对存储分派操作以及使用纯reducer设计状态更新。您甚至已经了解了如何使用reducer组合管理复杂状态并处理异步操作。这些示例过于简单，但这些概念是Redux的核心原则。如果您理解它们，那么您已准备好开始构建自己的Redux应用程序。接下来的挑战涵盖了有关state不变性的一些细节，但首先，这里是对迄今为止所学到的所有内容的回顾。
## Instructions
在本课程中，您将从头开始使用Redux实现一个简单的计数器。代码编辑器中提供了基础知识，但您必须填写详细信息！使用提供的名称并定义incAction和decAction操作创建者， decAction counterReducer() ， INCREMENT和DECREMENT操作类型，最后定义Redux store 。一旦完成，您应该能够发送INCREMENT或DECREMENT操作来增加或减少store保存的状态。祝你好运第一个Redux应用程序！
## Tests
```yml
tests:
- text: 动作创建者incAction应返回type等于INCREMENT值的动作对象
testString: 'assert(incAction().type ===INCREMENT, "The action creator incAction should return an action object with type equal to the value of INCREMENT");'
- text: 动作创建者decAction应与返回动作对象type等于的值DECREMENT
testString: 'assert(decAction().type === DECREMENT, "The action creator decAction should return an action object with type equal to the value of DECREMENT");'
- text: Redux存储应该以0 state初始化。
testString: 'assert(store.getState() === 0, "The Redux store should initialize with a state of 0.");'
- text: 在Redux存储上调度incAction应该将state增加1。
testString: 'assert((function() { const initialState = store.getState(); store.dispatch(incAction()); const incState = store.getState(); return initialState + 1 === incState })(), "Dispatching incAction on the Redux store should increment the state by 1.");'
- text: 在Redux存储上调度decAction应该将state减1。
testString: 'assert((function() { const initialState = store.getState(); store.dispatch(decAction()); const decState = store.getState(); return initialState - 1 === decState })(), "Dispatching decAction on the Redux store should decrement the state by 1.");'
- text: counterReducer应该是一个函数
testString: 'assert(typeof counterReducer === "function", "counterReducer should be a function");'
```
## Challenge Seed
```jsx
const INCREMENT = null; // define a constant for increment action types
const DECREMENT = null; // define a constant for decrement action types
const counterReducer = null; // define the counter reducer which will increment or decrement the state based on the action it receives
const incAction = null; // define an action creator for incrementing
const decAction = null; // define an action creator for decrementing
const store = null; // define the Redux store here, passing in your reducers
```
## Solution
```js
// solution required
```