# Fixes https://github.com/zeit/next.js/issues/5674
This adds config option
```js
// next.config.js
module.exports = {
crossOrigin: 'anonymous'
}
```
This config option is defined in the webpack Define Plugin at build.
`Head` and `NextScript` now use the config option, if it's not explicitly set on the element.
This value is now passed to Webpack so it can add it to scripts that it loads.
The value is now used in `PageLoader` (on the client) so it can add it to the scripts and links that it loads.
Using `<Head crossOrigin>` or `<NextScript crossOrigin>` is now deprecated.
* Convert render.js to typescript
* Compile tsx files too
* Remove internal renderErrorToHTML function
* Interopt component result
* requirePage doesn’t need async
* Move out enhancing logic into it’s own function
* Remove buildManifest from renderPage
* Move render into it’s own function
* Change let to const
* Move renderDocument into it’s own function
This PR will
- allow nextjs export to use all available CPU cores for rendering & writing pages by using child_process
- make use of async-sema to allow each thread to concurrently write multiple paths
- show a fancy progress bar while processing pages (with non-TTY fallback for CI web consoles)
The performance gain for my MacBook with 4 CPU cores went from ~25 pages per second to ~75 pages per second. Beefy CI machines with lots of cores should profit even more.
This PR Fixes#4920
So the problem is that when a next.js application is built on windows, the `pages-manifest.json` file is created with backslashes. If this built application is deployed to a linux hosting enviroment, the server will fail when trying to load the modules.
```
Error: Cannot find module '/user_code/next/server/bundles\pages\index.js
```
My simple solution is to modify the `pages-manifest.json` to always use linux separator (`/`), then also
modify `server/require.js` to, when requiring page, replace any separator (`\` or `/`) with current platform-specific file separator (`require('path').sep`).
The fix in `server/require.js` would be sufficient, but my opinion is that having some cross-platform consistency is nice.
This change was tested by bulding an application in windows and running it in linux and windows, aswell as building an application in linux and running it in linux and windows. The related tests was also run.
# Conflicts:
# test/integration/production/test/index.test.js
* Move send-html function and rewrite in typescript
* Move getPageFiles and convert to ts
* Move getPageFiles and convert to ts (#5841)
* Move getPageFiles and convert to ts
# Conflicts:
# packages/next-server/server/render.js
* Fix unit tests
We don't have to check if the file already exists here, since it's always in production mode (dev overrides the readBuildId method to always be `development`) If the file is not found (error is thrown) we check if the file exists. If not we throw a helpful error. In other cases we throw the original error.
Fixes#3705Fixes#4656
- No longer automatically dedupe certain tags. Only the ones we know are *never* going to be duplicate like charSet, title etc.
- Fix `key=""` behavior, making sure that if a unique key is provided tags are deduped based on that.
For example:
```jsx
<meta property='fb:pages' content='one'>
<meta property='fb:pages' content='two'>
```
Would currently cause
```jsx
<meta property='fb:pages' content='two'>
```
### After this change:
```jsx
<meta property='fb:pages' content='one'>
<meta property='fb:pages' content='two'>
```
Then if you use next/head multiple times / want to be able to override:
```jsx
<meta property='fb:pages' content='one' key="not-unique-key">
<meta property='fb:pages' content='two' key="not-unique-key">
```
Would cause:
```jsx
<meta property='fb:pages' content='two'>
```
As `key` gets deduped correctly after this PR, similar to how React itself works.
