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freeCodeCamp/curriculum/challenges/chinese/03-front-end-development-libraries/redux/use-a-switch-statement-to-handle-multiple-actions.md
Shaun Hamilton c2a11ad00d feat: add 'back/front end' in curriculum (#42596)
* chore: rename APIs and Microservices to include "Backend" (#42515)

* fix typo

* fix typo

* undo change

* Corrected grammar mistake

Corrected a grammar mistake by removing a comma.

* change APIs and Microservices cert title

* update title

* Change APIs and Microservices certi title

* Update translations.json

* update title

* feat(curriculum): rename apis and microservices cert

* rename folder structure

* rename certificate

* rename learn Markdown

* apis-and-microservices -> back-end-development-and-apis

* update backend meta

* update i18n langs and cypress test

Co-authored-by: Shaun Hamilton <shauhami020@gmail.com>

* fix: add development to front-end libraries (#42512)

* fix: added-the-word-Development-to-front-end-libraries

* fix/added-the-word-Development-to-front-end-libraries

* fix/added-word-development-to-front-end-libraries-in-other-related-files

* fix/added-the-word-Development-to-front-end-and-all-related-files

* fix/removed-typos-from-last-commit-in-index.md

* fix/reverted-changes-that-i-made-to-dependecies

* fix/removed xvfg

* fix/reverted changes that i made to package.json

* remove unwanted changes

* front-end-development-libraries changes

* rename backend certSlug and README

* update i18n folder names and keys

* test: add legacy path redirect tests

This uses serve.json from the client-config repo, since we currently use
that in production

* fix: create public dir before moving serve.json

* fix: add missing script

* refactor: collect redirect tests

* test: convert to cy.location for stricter tests

* rename certificate folder to 00-certificates

* change crowdin config to recognise new certificates location

* allow translations to be used

Co-authored-by: Nicholas Carrigan (he/him) <nhcarrigan@gmail.com>

* add forwards slashes to path redirects

* fix cypress path tests again

* plese cypress

* fix: test different challenge

Okay so I literally have no idea why this one particular challenge
fails in Cypress Firefox ONLY. Tom and I paired and spun a full build
instance and confirmed in Firefox the page loads and redirects as
expected. Changing to another bootstrap challenge passes Cypress firefox
locally. Absolutely boggled by this.

AAAAAAAAAAAAAAA

* fix: separate the test

Okay apparently the test does not work unless we separate it into
a different `it` statement.

>:( >:( >:( >:(

Co-authored-by: Sujal Gupta <55016909+heysujal@users.noreply.github.com>
Co-authored-by: Noor Fakhry <65724923+NoorFakhry@users.noreply.github.com>
Co-authored-by: Oliver Eyton-Williams <ojeytonwilliams@gmail.com>
Co-authored-by: Nicholas Carrigan (he/him) <nhcarrigan@gmail.com>
2021-08-13 21:57:13 -05:00

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id, title, challengeType, forumTopicId, dashedName
id title challengeType forumTopicId dashedName
5a24c314108439a4d4036151 使用 Switch 语句处理多个 Actions 6 301449 use-a-switch-statement-to-handle-multiple-actions

--description--

可以定义 Redux store 处理多种 action 类型。 假设在 Redux store 中管理用户身份验证。 希望用状态表示用户登录和注销。 使用 state 的 authenticated 属性表示它。 还需要使用 action creators 创建与用户登录和用户注销相对应的 action以及 action 对象本身。

--instructions--

代码编辑器为你创建了 store、actions、action creators。 通过编写 reducer 函数来处理多个身份验证操作。 可以在 reducer 里通过使用 JavaScript 的 switch 来响应不同的 action 事件。 这是编写 Redux reducers 的标准模式。 switch 语句应该切换 action.type 并返回适当的身份验证状态。

注意: 此时,不要担心 state 的不变性,因为在这个示例中它很小而且很简单。 所以对于每个操作都可以返回一个新对象,比如 {authenticated: true}。 另外,不要忘记在 switch 语句中写一个 default case返回当前的 state。 这是很重要的,因为当程序有多个 reducer当每一个 action 被 dispatch 时它们都会运行,即使 action 与该 reducer 无关。 在这种情况下,你要确保返回当前的 state

--hints--

调用函数 loginUser 应该返回一个 type 属性设置为字符串 LOGIN 的对象。

assert(loginUser().type === 'LOGIN');

调用函数 logoutUser 应该返回一个 type 属性设置为字符串 LOGOUT 的对象。

assert(logoutUser().type === 'LOGOUT');

store 应该设置一个 authenticated 属性设置为 false 的初始化对象。

assert(store.getState().authenticated === false);

dispatch loginUser应该将 store 中的 state 的 authenticated 值更新为 true

assert(
  (function () {
    const initialState = store.getState();
    store.dispatch(loginUser());
    const afterLogin = store.getState();
    return (
      initialState.authenticated === false && afterLogin.authenticated === true
    );
  })()
);

dispatch logoutUser 应该将 store 中的 state 的 authenticated 值更新为 false

assert(
  (function () {
    store.dispatch(loginUser());
    const loggedIn = store.getState();
    store.dispatch(logoutUser());
    const afterLogout = store.getState();
    return (
      loggedIn.authenticated === true && afterLogout.authenticated === false
    );
  })()
);

authReducer 函数应该使用 switch 语句处理多个 action 类型。

(getUserInput) =>
  assert(
    getUserInput('index').toString().includes('switch') &&
      getUserInput('index').toString().includes('case') &&
      getUserInput('index').toString().includes('default')
  );

--seed--

--seed-contents--

const defaultState = {
  authenticated: false
};

const authReducer = (state = defaultState, action) => {
  // Change code below this line

  // Change code above this line
};

const store = Redux.createStore(authReducer);

const loginUser = () => {
  return {
    type: 'LOGIN'
  }
};

const logoutUser = () => {
  return {
    type: 'LOGOUT'
  }
};

--solutions--

const defaultState = {
  authenticated: false
};

const authReducer = (state = defaultState, action) => {

  switch (action.type) {

    case 'LOGIN':
      return {
        authenticated: true
      }

    case 'LOGOUT':
      return {
        authenticated: false
      }

    default:
      return state;

  }

};

const store = Redux.createStore(authReducer);

const loginUser = () => {
  return {
    type: 'LOGIN'
  }
};

const logoutUser = () => {
  return {
    type: 'LOGOUT'
  }
};