reactjs - react : Load component's CSS only when component is rendered

Question

# MyComponent.js

import React from 'react'
import './MyComponentStyle.css'

export default class MyComponent extends React.Component {
   ....
}


# App.js

import React from 'react'
import ReactDOM from 'react-dom'
import { Route, Switch, BrowserRouter } from 'react-router-dom'
import MyComponent from './MyComponent'
import PageNotFound from './PageNotFound'

ReactDOM.render(
  <BrowserRouter>
    <Switch>
        <Route exact path='/mycomponent' component={MyComponent}/>
        <Route component={PageNotFound} />
      </Switch>
  </BrowserRouter>,
  document.getElementById('root'));

当我转到 /mycomponent 时，MyComponent 使用其 css 进行渲染。但是当我转到任何其他网址时，MyComponentStyle.css 仍然可以在 html 的 Head 中看到。有没有办法仅当组件在其路由上渲染时渲染相应的组件CSS？

Answer 1

Webpack v2 引入了一项名为 dynamic import 的功能通过import()。您可以将 CSS 导入移动到 render 或 componentWillMount 方法中，由 bool 变量保护以确保仅加载一次。

import React from 'react'

let cssLoaded = false;

export default class MyComponent extends React.Component {
    render() {
        if (cssLoaded === false) {
            cssLoaded = true;
            import('./MyComponentStyle.css');
        }

        // other stuff
    }
}