Pen Settings

HTML

CSS

CSS Base

Vendor Prefixing

Add External Stylesheets/Pens

Any URL's added here will be added as <link>s in order, and before the CSS in the editor. If you link to another Pen, it will include the CSS from that Pen. If the preprocessor matches, it will attempt to combine them before processing.

+ add another resource

JavaScript

Babel includes JSX processing.

Add External Scripts/Pens

Any URL's added here will be added as <script>s in order, and run before the JavaScript in the editor. You can use the URL of any other Pen and it will include the JavaScript from that Pen.

+ add another resource

Packages

Add Packages

Search for and use JavaScript packages from npm here. By selecting a package, an import statement will be added to the top of the JavaScript editor for this package.

Behavior

Save Automatically?

If active, Pens will autosave every 30 seconds after being saved once.

Auto-Updating Preview

If enabled, the preview panel updates automatically as you code. If disabled, use the "Run" button to update.

Format on Save

If enabled, your code will be formatted when you actively save your Pen. Note: your code becomes un-folded during formatting.

Editor Settings

Code Indentation

Want to change your Syntax Highlighting theme, Fonts and more?

Visit your global Editor Settings.

HTML

              
                
              
            
!

CSS

              
                
              
            
!

JS

              
                import React, {PureComponent, createElement} from 'react';
import {render} from 'react-dom';
import {HashRouter, Route, Link} from 'react-router-dom';
import PageHome from './pages/home';

/**
 * 异步加载组件
 * @param load 组件加载函数,load 函数会返回一个 Promise,在文件加载完成时 resolve
 * @returns {AsyncComponent} 返回一个高阶组件用于封装需要异步加载的组件
 */
function getAsyncComponent(load) {
  return class AsyncComponent extends PureComponent {

    componentDidMount() {
      // 在高阶组件 DidMount 时才去执行网络加载步骤
      load().then(({default: component}) => {
        // 代码加载成功,获取到了代码导出的值,调用 setState 通知高阶组件重新渲染子组件
        this.setState({
          component,
        })
      });
    }

    render() {
      const {component} = this.state || {};
      // component 是 React.Component 类型,需要通过 React.createElement 生产一个组件实例
      return component ? createElement(component) : null;
    }
  }
}

// 根组件
function App() {
  return (
    <HashRouter>
      <div>
        <nav>
          <Link to='/'>Home</Link> | <Link to='/about'>About</Link> | <Link to='/login'>Login</Link>
        </nav>
        <hr/>
        <Route exact path='/' component={PageHome}/>
        <Route path='/about' component={getAsyncComponent(
          // 异步加载函数,异步地加载 PageAbout 组件
          () => import(/* webpackChunkName: 'page-about' */'./pages/about')
        )}
        />
        <Route path='/login' component={getAsyncComponent(
          // 异步加载函数,异步地加载 PageAbout 组件
          () => import(/* webpackChunkName: 'page-login' */'./pages/login')
        )}
        />
      </div>
    </HashRouter>
  )
}

// 渲染根组件
render(<App/>, window.document.getElementById('app'));
              
            
!
999px

Console