用事件总线模式分割开3个模块
3个子组件中数据独立处理
Header中做input提交到父组件，然后在main中接收
App.js只做事件转发：
render() {
return (
<section className="todoapp">
<Header eventEmitter={eventEmitter} />
<Main eventEmitter={eventEmitter} />
<Footer eventEmitter={eventEmitter}/>
</section>
);
}Header.js：
handleInput = (value) => {
// 转发事件
this.props.eventEmitter.emit('inputAdd', value);
}
handleKeyDown(e) {
if (e.keyCode !== 13) {
return;
}
e.preventDefault();
let val = this.inputText.value
if (val) {
this.handleInput(val);
this.inputText.value = '';
}
}
render () {
return (
<div>
<header className="header">
// 省略...
<input
ref={(el) => { this.inputText = el }}
onKeyDown = {this.handleKeyDown}
/>
</header>
</div>
)
}main.js：
componentDidMount () {
// 挂载完成后接受事件监听
this.props.eventEmitter.on('inputAdd', (inputVal) => {
const _todos = addTodo(this.state.todos, inputVal);
this.updateTodo(_todos);
});
this.props.eventEmitter.on('nowShowing', (showType) => {
this.handelNowShowing(showType);
});
this.props.eventEmitter.on('clearCompleted', () => {
this.onClearCompleted();
});
}先做事件总线模式，此优化暂时搁置
上一版中我在Main.js，Footer.js中做了组件内容显示与否的判断，此时即使没有数据依然会渲染组件，并且组件不会被卸载 导致componentWillUnmount无法被触发
Main.js:
export default class Main extends Component {
componentWillUnmount() {
// 无法被触发
}
render () {
const todos = this.props.todos;
const nowShowing = this.props.nowShowing;
let main = null;
if (todos.length) {
main = (
<section className='main' >
<!-- 组件内容 -->
</section>
)
}
return (main)
}改版后把判断放入App.js内，Main 和 Footer 中正常渲染组件内容，这样当没有数据时Main，Footer能被正确卸载掉
class App extends Component {
constructor () {
super();
this.state = {
name: "Todos",
todos: Toolkit.util.store(_NAME_)
};
}
render () {
let main = null, footer = null;
if (this.state.todos.length) {
main = (
<Main />
);
footer = (
<Footer />
)
}
return (
<section className="todoapp">
<Header />
{main}
{footer}
</section>
);
}
}简单的父子组件传值操作，所有操作都由子组件或孙组件一级级往上传到App.js内进行数据操作，然后再向下分发进行渲染
This project was bootstrapped with Create React App.
In the project directory, you can run:
Runs the app in the development mode.
Open http://localhost:3000 to view it in the browser.
The page will reload if you make edits.
You will also see any lint errors in the console.
Launches the test runner in the interactive watch mode.
See the section about running tests for more information.
Builds the app for production to the build folder.
It correctly bundles React in production mode and optimizes the build for the best performance.
The build is minified and the filenames include the hashes.
Your app is ready to be deployed!
See the section about deployment for more information.
Note: this is a one-way operation. Once you eject, you can’t go back!
If you aren’t satisfied with the build tool and configuration choices, you can eject at any time. This command will remove the single build dependency from your project.
Instead, it will copy all the configuration files and the transitive dependencies (Webpack, Babel, ESLint, etc) right into your project so you have full control over them. All of the commands except eject will still work, but they will point to the copied scripts so you can tweak them. At this point you’re on your own.
You don’t have to ever use eject. The curated feature set is suitable for small and middle deployments, and you shouldn’t feel obligated to use this feature. However we understand that this tool wouldn’t be useful if you couldn’t customize it when you are ready for it.
By default, the generated project uses the latest version of React.
You can refer to the React documentation for more information about supported browsers.
This project supports a superset of the latest JavaScript standard.
In addition to ES6 syntax features, it also supports:
- Exponentiation Operator (ES2016).
- Async/await (ES2017).
- Object Rest/Spread Properties (stage 3 proposal).
- Dynamic import() (stage 3 proposal)
- Class Fields and Static Properties (part of stage 3 proposal).
- JSX and Flow syntax.
Learn more about different proposal stages.
While we recommend using experimental proposals with some caution, Facebook heavily uses these features in the product code, so we intend to provide codemods if any of these proposals change in the future.
Note that the project only includes a few ES6 polyfills:
Object.assign()viaobject-assign.Promiseviapromise.fetch()viawhatwg-fetch.
If you use any other ES6+ features that need runtime support (such as Array.from() or Symbol), make sure you are including the appropriate polyfills manually, or that the browsers you are targeting already support them.
Also note that using some newer syntax features like for...of or [...nonArrayValue] causes Babel to emit code that depends on ES6 runtime features and might not work without a polyfill. When in doubt, use Babel REPL to see what any specific syntax compiles down to.
Note: this feature is available with
react-scripts@0.2.0and higher.
The step below is important!
If you skip it, your app will not deploy correctly.
Open your package.json and add a homepage field for your project:
"homepage": "https://myusername.github.io/my-app",or for a GitHub user page:
"homepage": "https://myusername.github.io",Create React App uses the homepage field to determine the root URL in the built HTML file.
Now, whenever you run npm run build, you will see a cheat sheet with instructions on how to deploy to GitHub Pages.
To publish it at https://myusername.github.io/my-app, run:
npm install --save gh-pagesAlternatively you may use yarn:
yarn add gh-pagesAdd the following scripts in your package.json:
"scripts": {
+ "predeploy": "npm run build",
+ "deploy": "gh-pages -d build",
"start": "react-scripts start",
"build": "react-scripts build",The predeploy script will run automatically before deploy is run.
If you are deploying to a GitHub user page instead of a project page you'll need to make two additional modifications:
- First, change your repository's source branch to be any branch other than master.
- Additionally, tweak your
package.jsonscripts to push deployments to master:
"scripts": {
"predeploy": "npm run build",
- "deploy": "gh-pages -d build",
+ "deploy": "gh-pages -b master -d build",Then run:
npm run deployFinally, make sure GitHub Pages option in your GitHub project settings is set to use the gh-pages branch:
You can configure a custom domain with GitHub Pages by adding a CNAME file to the public/ folder.
GitHub Pages doesn’t support routers that use the HTML5 pushState history API under the hood (for example, React Router using browserHistory). This is because when there is a fresh page load for a url like http://user.github.io/todomvc/todos/42, where /todos/42 is a frontend route, the GitHub Pages server returns 404 because it knows nothing of /todos/42. If you want to add a router to a project hosted on GitHub Pages, here are a couple of solutions:
- You could switch from using HTML5 history API to routing with hashes. If you use React Router, you can switch to
hashHistoryfor this effect, but the URL will be longer and more verbose (for example,http://user.github.io/todomvc/#/todos/42?_k=yknaj). Read more about different history implementations in React Router. - Alternatively, you can use a trick to teach GitHub Pages to handle 404 by redirecting to your
index.htmlpage with a special redirect parameter. You would need to add a404.htmlfile with the redirection code to thebuildfolder before deploying your project, and you’ll need to add code handling the redirect parameter toindex.html. You can find a detailed explanation of this technique in this guide.
If you have ideas for more “How To” recipes that should be on this page, let us know or contribute some!