* 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>
88 lines
2.3 KiB
Markdown
88 lines
2.3 KiB
Markdown
---
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id: 5a24c314108439a4d403617c
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title: 使用生命周期方法:componentWillMount
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challengeType: 6
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forumTopicId: 301423
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dashedName: use-the-lifecycle-method-componentwillmount
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---
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# --description--
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React 组件有几种特殊方法,可以在组件生命周期的特定点执行操作。 这些称为生命周期方法或生命周期钩子,允许在特定时间点捕获组件。 这可以在渲染之前、更新之前、接收 props 之前、卸载之前等等。 以下是一些主要生命周期方法的列表: `componentWillMount()` `componentDidMount()` `shouldComponentUpdate()` `componentDidUpdate()` `componentWillUnmount()` 接下来的几节课将讲述这些生命周期方法的一些基本用例。
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**注意:** `componentWillMount` 生命周期方法会在版本 16.X 废弃在版本 17 移除。 [(来源)](https://reactjs.org/blog/2018/03/27/update-on-async-rendering.html)
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# --instructions--
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当组件被挂载到 DOM 时,`componentWillMount()` 方法在 `render()` 方法之前被调用。 在`componentWillMount()`中将一些内容记录到控制台 -- 可能需要打开浏览器控制台以查看输出。
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# --hints--
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`MyComponent` 应该渲染一个 `div` 元素。
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```js
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assert(
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(function () {
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const mockedComponent = Enzyme.mount(React.createElement(MyComponent));
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return mockedComponent.find('div').length === 1;
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})()
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);
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```
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应该在 `componentWillMount` 中调用 `console.log`。
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```js
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assert(
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(function () {
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const lifecycle = React.createElement(MyComponent)
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.type.prototype.componentWillMount.toString()
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.replace(/ /g, '');
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return lifecycle.includes('console.log(');
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})()
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);
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```
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# --seed--
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## --after-user-code--
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```jsx
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ReactDOM.render(<MyComponent />, document.getElementById('root'))
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```
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## --seed-contents--
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```jsx
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class MyComponent extends React.Component {
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constructor(props) {
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super(props);
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}
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componentWillMount() {
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// Change code below this line
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// Change code above this line
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}
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render() {
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return <div />
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}
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};
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```
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# --solutions--
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```jsx
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class MyComponent extends React.Component {
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constructor(props) {
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super(props);
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}
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componentWillMount() {
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// Change code below this line
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console.log('Component is mounting...');
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// Change code above this line
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}
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render() {
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return <div />
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}
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};
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```
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