* 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>
4.2 KiB
id, title, challengeType, forumTopicId, dashedName
id | title | challengeType | forumTopicId | dashedName |
---|---|---|---|---|
5a24c314108439a4d4036174 | 將 this 綁定到 Class 方法上 | 6 | 301379 | bind-this-to-a-class-method |
--description--
除了設置和更新 state
之外,還可以爲組件類定義方法。 類方法通常需要使用 this
關鍵字,以便它可以訪問方法中類的屬性(例如 state
和 props
)。 有幾種方法可以讓類方法訪問 this
。
一種常見的方法是在構造函數中顯式地綁定 this
,這樣當組件初始化時,this
就會綁定到類方法。 你可能已經注意到上一個挑戰在構造函數中的 handleClick
方法使用了 this.handleClick = this.handleClick.bind(this)
。 然後,當在類方法中調用像 this.setState()
這樣的函數時,this
指的是這個類,而不是 undefined
。
注意: this
關鍵字是 JavaScript 中最令人困惑的方面之一,但它在 React 中扮演着重要的角色。 雖然它的行爲在這裏是完全正常的,但是這些課程並不深入研究this
,所以如果以上內容令你感到困惑,請參考其他課程!
--instructions--
代碼編輯器有一個帶有 state
的組件,用於跟蹤項目計數。 它還有一個方法,允許設置文本爲 You clicked!
。 但是,該方法不起作用,因爲它使用了未定義的 this
關鍵字。 可以通過將 this
顯式綁定到組件構造函數中的 handleClick()
方法來修復它。
接下來,向 render 方法中的 button
元素添加一個單擊處理程序。 當按鈕接收到單擊事件時,它應該觸發 handleClick()
方法。 記住,傳遞給 onClick
處理程序的方法需要使用花括號,因爲它應該直接被解釋爲 JavaScript。
完成上述步驟後,可以單擊按鈕並看到 You clicked!
。
--hints--
MyComponent
應返回 div
元素,該元素按順序包含兩個元素,一個按鈕和一個 h1
元素。
assert(
Enzyme.mount(React.createElement(MyComponent)).find('div').length === 1 &&
Enzyme.mount(React.createElement(MyComponent))
.find('div')
.childAt(0)
.type() === 'button' &&
Enzyme.mount(React.createElement(MyComponent))
.find('div')
.childAt(1)
.type() === 'h1'
);
MyComponent
的 state 應該使用鍵值對 { text: "Hello" }
,進行初始化。
assert(
Enzyme.mount(React.createElement(MyComponent)).state('text') === 'Hello'
);
單擊 button
元素應該運行 handleClick
方法,並使 state text
爲 You clicked!
。
async () => {
const waitForIt = (fn) =>
new Promise((resolve, reject) => setTimeout(() => resolve(fn()), 250));
const mockedComponent = Enzyme.mount(React.createElement(MyComponent));
const first = () => {
mockedComponent.setState({ text: 'Hello' });
return waitForIt(() => mockedComponent.state('text'));
};
const second = () => {
mockedComponent.find('button').simulate('click');
return waitForIt(() => mockedComponent.state('text'));
};
const firstValue = await first();
const secondValue = await second();
assert(firstValue === 'Hello' && secondValue === 'You clicked!');
};
--seed--
--after-user-code--
ReactDOM.render(<MyComponent />, document.getElementById('root'))
--seed-contents--
class MyComponent extends React.Component {
constructor(props) {
super(props);
this.state = {
text: "Hello"
};
// Change code below this line
// Change code above this line
}
handleClick() {
this.setState({
text: "You clicked!"
});
}
render() {
return (
<div>
{ /* Change code below this line */ }
<button>Click Me</button>
{ /* Change code above this line */ }
<h1>{this.state.text}</h1>
</div>
);
}
};
--solutions--
class MyComponent extends React.Component {
constructor(props) {
super(props);
this.state = {
text: "Hello"
};
this.handleClick = this.handleClick.bind(this);
}
handleClick() {
this.setState({
text: "You clicked!"
});
}
render() {
return (
<div>
<button onClick = {this.handleClick}>Click Me</button>
<h1>{this.state.text}</h1>
</div>
);
}
};