使用React.lazy和Suspense进行组件延迟加载

import React, { Component, Suspense } from "react";
const LazyPDFDocument = React.lazy(() => import("./PDFPreview"));

<Suspense fallback={<div>Loading...</div>}>
     <LazyPDFDocument title={greeting} />
</Suspense>

//React.lazy加载的组件只能在<React.Suspense>组件下使用