ee1e8abd87
* feat(tools): add seed/solution restore script * chore(curriculum): remove empty sections' markers * chore(curriculum): add seed + solution to Chinese * chore: remove old formatter * fix: update getChallenges parse translated challenges separately, without reference to the source * chore(curriculum): add dashedName to English * chore(curriculum): add dashedName to Chinese * refactor: remove unused challenge property 'name' * fix: relax dashedName requirement * fix: stray tag Remove stray `pre` tag from challenge file. Signed-off-by: nhcarrigan <nhcarrigan@gmail.com> Co-authored-by: nhcarrigan <nhcarrigan@gmail.com>
116 lines
2.7 KiB
Markdown
116 lines
2.7 KiB
Markdown
---
|
||
id: 5a24c314108439a4d4036143
|
||
title: 提取状态逻辑给 Redux
|
||
challengeType: 6
|
||
forumTopicId: 301429
|
||
dashedName: extract-state-logic-to-redux
|
||
---
|
||
|
||
# --description--
|
||
|
||
完成 React 组件后，我们需要把在本地`状态`执行的逻辑移到 Redux 中，这是为小规模 React 应用添加 Redux 的第一步。该应用的唯一功能是把用户的新消息添加到无序列表中。下面我们用简单的示例来演示 React 和 Redux 之间的配合。
|
||
|
||
# --instructions--
|
||
|
||
首先，定义 action 的类型 'ADD'，将其设置为常量`ADD`。接着，定义创建 action 的函数`addMessage()`，用该函数创建添加消息的 action，把`message`传给创建 action 的函数并返回包含该消息的`action`
|
||
|
||
接着，创建名为`messageReducer()`的 reducer 方法，为这些消息处理状态。初始状态应为空数组。reducer 向状态中的消息数组添加消息，或返回当前状态。最后，创建 Redux store 并传给 reducer。
|
||
|
||
# --hints--
|
||
|
||
应存在一个值为字符串`ADD`的常量`ADD`。
|
||
|
||
```js
|
||
assert(ADD === 'ADD');
|
||
```
|
||
|
||
创建 action 的函数`addMessage`应返回`type`等于`ADD`的对象，其返回的消息即被传入的消息。
|
||
|
||
```js
|
||
assert(
|
||
(function () {
|
||
const addAction = addMessage('__TEST__MESSAGE__');
|
||
return addAction.type === ADD && addAction.message === '__TEST__MESSAGE__';
|
||
})()
|
||
);
|
||
```
|
||
|
||
`messageReducer`应是一个函数。
|
||
|
||
```js
|
||
assert(typeof messageReducer === 'function');
|
||
```
|
||
|
||
存在一个 store 且其初始状态为空数组。
|
||
|
||
```js
|
||
assert(
|
||
(function () {
|
||
const initialState = store.getState();
|
||
return typeof store === 'object' && initialState.length === 0;
|
||
})()
|
||
);
|
||
```
|
||
|
||
分发`addMessage`到 store 应添加新消息到状态中消息数组。
|
||
|
||
```js
|
||
assert(
|
||
(function () {
|
||
const initialState = store.getState();
|
||
const isFrozen = DeepFreeze(initialState);
|
||
store.dispatch(addMessage('__A__TEST__MESSAGE'));
|
||
const addState = store.getState();
|
||
return isFrozen && addState[0] === '__A__TEST__MESSAGE';
|
||
})()
|
||
);
|
||
```
|
||
|
||
`messageReducer`被其它任何 actions 调用时应返回当前状态。
|
||
|
||
```js
|
||
assert(
|
||
(function () {
|
||
const addState = store.getState();
|
||
store.dispatch({ type: 'FAKE_ACTION' });
|
||
const testState = store.getState();
|
||
return addState === testState;
|
||
})()
|
||
);
|
||
```
|
||
|
||
# --seed--
|
||
|
||
## --seed-contents--
|
||
|
||
```jsx
|
||
// Define ADD, addMessage(), messageReducer(), and store here:
|
||
```
|
||
|
||
# --solutions--
|
||
|
||
```jsx
|
||
const ADD = 'ADD';
|
||
|
||
const addMessage = (message) => {
|
||
return {
|
||
type: ADD,
|
||
message
|
||
}
|
||
};
|
||
|
||
const messageReducer = (state = [], action) => {
|
||
switch (action.type) {
|
||
case ADD:
|
||
return [
|
||
...state,
|
||
action.message
|
||
];
|
||
default:
|
||
return state;
|
||
}
|
||
};
|
||
|
||
const store = Redux.createStore(messageReducer);
|
||
```
|