Files
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
5a24c314108439a4d4036176 使用 State 切換元素 6 301421 use-state-to-toggle-an-element

--description--

有時可能在更新狀態的時候想知道上一個狀態是什麼。 但是狀態更新是異步的,這意味着 React 可能會把多個 setState() 集中在一起批量更新。 所以計算下一個值時 this.state 或者 this.props 不能作爲當前值。 所以最好不要寫如下的代碼:

this.setState({
  counter: this.state.counter + this.props.increment
});

正確的做法是,給 setState 傳入一個函數,這個函數可以訪問 state 和 props。 給 setState 傳入函數可以保證 state 和 props 是正確的值。 代碼可以重寫爲這樣:

this.setState((state, props) => ({
  counter: state.counter + props.increment
}));

如果只需要 state,那麼用下面沒有 props 的格式也是可以的:

this.setState(state => ({
  counter: state.counter + 1
}));

注意一定要把 object 放在括號裏,否則 JavaScript 會認爲這只是代碼片段。

--instructions--

MyComponent 有一個初始值爲 falsevisibility 屬性。 如果 visibility 的值爲 truerender 方法返回一個視圖,如果爲 false返回另一個視圖。

目前,無法更新組件 state 中的 visibility 屬性, 該值應在 true 和 false 之間來回切換。 按鈕上有一個單擊處理程序,它觸發一個名爲 toggleVisibility() 的類方法。 給函數傳入 setState 來定義此方法,以便 visibilitystate 在調用方法時切換到相反的值。 如果 visibilityfalse,則該方法將其設置爲true,反之亦然。

最後,單擊按鈕以查看基於其 state 的組件的條件渲染。

提示: 不要忘記將 this 關鍵字綁定到 constructor 中的方法上!

--hints--

MyComponent 應該返回一個 div 元素,其中包含一個 button 元素。

assert.strictEqual(
  Enzyme.mount(React.createElement(MyComponent)).find('div').find('button')
    .length,
  1
);

MyComponent 應該使用設置爲 falsevisibility 屬性來初始化其 state。

assert.strictEqual(
  Enzyme.mount(React.createElement(MyComponent)).state('visibility'),
  false
);

單擊按鈕元素應在 truefalse 之間切換 visibility 屬性的狀態。

(() => {
  const mockedComponent = Enzyme.mount(React.createElement(MyComponent));
  const first = () => {
    mockedComponent.setState({ visibility: false });
    return mockedComponent.state('visibility');
  };
  const second = () => {
    mockedComponent.find('button').simulate('click');
    return mockedComponent.state('visibility');
  };
  const third = () => {
    mockedComponent.find('button').simulate('click');
    return mockedComponent.state('visibility');
  };
  const firstValue = first();
  const secondValue = second();
  const thirdValue = third();
  assert(!firstValue && secondValue && !thirdValue);
})();

應該給 setState 傳入一個匿名函數。

const paramRegex = '[a-zA-Z$_]\\w*(,[a-zA-Z$_]\\w*)?';
assert(
  new RegExp(
    'this\\.setState\\((function\\(' +
      paramRegex +
      '\\){|([a-zA-Z$_]\\w*|\\(' +
      paramRegex +
      '\\))=>)'
  ).test(__helpers.removeWhiteSpace(code))
);

不要在 setState 裏面使用 this

assert(!/this\.setState\([^}]*this/.test(code));

--seed--

--after-user-code--

ReactDOM.render(<MyComponent />, document.getElementById('root'));

--seed-contents--

class MyComponent extends React.Component {
  constructor(props) {
    super(props);
    this.state = {
      visibility: false
    };
    // Change code below this line

    // Change code above this line
  }
  // Change code below this line

  // Change code above this line
  render() {
    if (this.state.visibility) {
      return (
        <div>
          <button onClick={this.toggleVisibility}>Click Me</button>
          <h1>Now you see me!</h1>
        </div>
      );
    } else {
      return (
        <div>
          <button onClick={this.toggleVisibility}>Click Me</button>
        </div>
      );
    }
  }
}

--solutions--

class MyComponent extends React.Component {
  constructor(props) {
    super(props);
    this.state = {
      visibility: false
    };
    this.toggleVisibility = this.toggleVisibility.bind(this);
  }
  toggleVisibility() {
    this.setState(state => ({
      visibility: !state.visibility
    }));
  }
  render() {
    if (this.state.visibility) {
      return (
        <div>
          <button onClick={this.toggleVisibility}>Click Me</button>
          <h1>Now you see me!</h1>
        </div>
      );
    } else {
      return (
        <div>
          <button onClick={this.toggleVisibility}>Click Me</button>
        </div>
      );
    }
  }
}