不变式违例：元素types无效：期望一个string（用于内置组件）或类/函数。 反应路由器v4
我对reactjs比较陌生，正在使用react-router v4testing基本的服务器端渲染，但是我无法越过这个错误，从几个小时以来一直在尝试。 我已经尝试了我在谷歌find的每一个解决scheme，但他们似乎没有工作。
这里是server.js代码：
import Express from 'express'; import React from 'react'; import { renderToString } from 'react-dom/server'; import { StaticRouter } from 'react-router' import MyRoutes from './routes/routes.js'; ... app.get('*', (req, res) => { let markup = `<!DOCTYPE html> <html lang="en"> <body> ${renderToString(<StaticRouter location={req.url} context={{}}><MyRoutes/></StaticRouter>)} </body> </html>`; res.write(markup); res.end(); }); 问题似乎与以下代码：
./routes/routes.js代码：
import React from 'react'; import { Match, Miss } from 'react-router'; const componentTest = () => ( <div> Testing a component </div> ); export default () => ( <div> <Match exactly={true} pattern="/" component={componentTest} /> </div> );
现在， 如果我删除匹配标记线，我得到空白页，没有错误。 但是，如果匹配标签行在那里，我得到以下错误：
Warning: React.createElement: type is invalid -- expected a string (for built-in components) or a class/function (for composite components) but got: undefined. You likely forgot to export your component from the file it's defined in. in Unknown in Router (created by StaticRouter) in StaticRouter Invariant Violation: Element type is invalid: expected a string (for built-in components) or a class/function (for composite components) but got: undefined. You likely forgot to export your component from the file it's defined in. Check the render method of `StatelessComponent`. at invariant (/home/ubuntu/workspace/node_modules/react-dom/node_modules/fbjs/lib/invariant.js:44:15) at instantiateReactComponent (/home/ubuntu/workspace/node_modules/react-dom/lib/instantiateReactComponent.js:74:56) at instantiateChild (/home/ubuntu/workspace/node_modules/react-dom/lib/ReactChildReconciler.js:44:28) at /home/ubuntu/workspace/node_modules/react-dom/lib/ReactChildReconciler.js:71:16 at traverseAllChildrenImpl (/home/ubuntu/workspace/node_modules/react-dom/lib/traverseAllChildren.js:77:5) at traverseAllChildren (/home/ubuntu/workspace/node_modules/react-dom/lib/traverseAllChildren.js:172:10) at Object.ReactChildReconciler.instantiateChildren (/home/ubuntu/workspace/node_modules/react-dom/lib/ReactChildReconciler.js:70:7) at ReactDOMComponent.ReactMultiChild.Mixin._reconcilerInstantiateChildren (/home/ubuntu/workspace/node_modules/react-dom/lib/ReactMultiChild.js:187:41) at ReactDOMComponent.ReactMultiChild.Mixin.mountChildren (/home/ubuntu/workspace/node_modules/react-dom/lib/ReactMultiChild.js:226:27) at ReactDOMComponent.Mixin._createContentMarkup (/home/ubuntu/workspace/node_modules/react-dom/lib/ReactDOMComponent.js:653:32)
任何帮助将非常感激。
解决这个问题的是Tharaka Wijebandara在评论中给出的。
问题是Match已经被react-router v4 Route所取代。 所以用这行replaceMatch标签行解决了它：
<Route exact path="/" component={componentTest} />
来源： https ： //reacttraining.com/react-router/web/api/Route