Did not expect server HTML to contain a <div> in <main>

Question

I'm working in a project that uses:

• react/react-dom@16.9.0
• @loadable/component
• styled-components
• react-router-dom

The application renders both server side and client side.

I'm using @loadable/component to dynamically code split this way.

router.tsx

import * as React from 'react'
import loadable from '@loadable/component'
import { Route, Switch } from 'react-router-dom'

const NotFound = loadable(() =>
  import('../components/NotFound/NotFound' /* webpackChunkName: "notfound" */)
)

const routes = (
  <Switch>
    <Route component={NotFound} />
  </Switch>
)

export default routes

When loading the page, this error appear on the console and the page seems to flick for a second.

react-dom.development.js:546 Warning: Did not expect server HTML to contain a <div> in <main>.

When I check the output in both sides (server/client), they are identical.

When I remove @loadable/component like bellow, it works and the error is gone.

router-without-loadable.tsx

import * as React from 'react'
import { Route, Switch } from 'react-router-dom'
import NotFound from '../components/NotFound/NotFound'

const routes = (
  <Switch>
    <Route component={NotFound} />
  </Switch>
)

export default routes

Seems to be something to do with @loadable/component but I'm not 100% sure.

Answer 1

Finally have an answer for this:

1. For @loadable/component to work properly, you need to put the magic webpack comment (/* webpackChunkName: "notfound" */) before the path of the file this way.

const NotFound = loadable(() =>
  import(/* webpackChunkName: "notfound" */ '../components/NotFound/NotFound')
)

Reference:

https://github.com/smooth-code/loadable-components/issues/23

2. And more important, in the server side, you need to wrap you app in a ChunkExtractorManager and pass the client extractor (I was passing the server extractor, it's not very clear in the docs).

const statsFile = path.resolve('./wwwroot/dist/loadable-stats.json')
const extractor = new ChunkExtractor({ 
  statsFile, 
  entrypoints: ['client'] // name of the proper webpack endpoint (default: main)
})

<ChunkExtractorManager extractor={extractor}>
  <App />
</ChunkExtractorManager>

Here is a proper clear example on how to implement it:

https://github.com/iamssen/seed

Update 24.09.2019

Added to the official docs

https://www.smooth-code.com/open-source/loadable-components/docs/server-side-rendering/#chunkextractor-entrypoints