Fixes#4495
Here's my approach for replacing the XHR on-demand-entries pinger #1364#4495. I'm not sure if this is the way everyone wants to accomplish this since I saw mention of using a separate server and port for the dynamic entries websocket, but thought this would be a fairly clean solution since it doesn't need that.
With this method the only change when using a custom server is you have to listen for the upgrade event and pass it to next.getRequestHandler(). Example:
```
const server = app.listen(port)
const handleRequest = next.getRequestHandler()
if(dev) {
server.on('upgrade', handleRequest)
}
```
* Compile pages to .next/static/<buildid>/pages/<page>
* Fix test
* Export class instead of using exports
* Use constant for static directory
* Add comment about what the middleware does
* Dump address.
* Use zero as the port.
* Limit test cases.
* throw address.
* Fail a specific error.
* Set a port manually.
* Make sure jest is working properly.
* Set the jest timeout time to 5 min.
* Run the actual test
* Run all production tests on Travis.
* Set the Jest default timeout to 5 min for all integration tests.
* Remove production only testing.
* Remove unwanted console.log
* Remove the addition number from test case
* Set the static export test jest timeout to 5 min.
* Run tests again if they failed once.
* Introduce script tag based page loading system.
* Call ensurePage only in the dev mode.
* Implement router using the page-loader.
* Fix a typo and remove unwanted code.
* Fix some issues related to rendering.
* Fix production tests.
* Fix ondemand test cases.
* Fix unit tests.
* Get rid of eval completely.
* Remove all the inline code.
* Remove the json-pages plugin.
* Rename NEXT_PAGE_LOADER into __NEXT_PAGE_LOADER__
* Rename NEXT_LOADED_PAGES into __NEXT_LOADED_PAGES__
* Remove some unwanted code.
* Load everything async.
* Remove lib/eval-script.js
We no longer need it.
* Move webpack idle wait code to the page-loader.
Because that's the place to do it.
* Remove pageNotFound key from the error.
* Remove unused error field 'buildError'
* Add much better logic to normalize routes.
* Get rid of mitt.
* Introduce a better way to register pages.
* Came back to the mitt() based page-loader.
* Add link rel=preload support.
* Add assetPrefix support to add support for CDNs.
* Add assetPrefix support for preload links.
* Update readme.md
* Add a plan for dynamic entry middleware.
* Use dynamic pages middleware to load pages in dev.
* Add the first version of middleware but not tested.
* Integrated.
* Disable prefetching in development.
Otherwise it'll discard the use of dynamic-entries.
* Build custom document and error always.
* Refactor code base.
* Change branding as on-demand entries.
* Fix tests.
* Add a client side pinger for on-demand-entries.
* Dispose inactive entries.
* Add proper logs.
* Update grammer changes.
* Add integration tests for ondemand entries.
* Improve ondemand entry disposing logic.
* Try to improve testing.
* Make sure entries are not getting disposed in basic integration tests.
* Resolve conflicts.
* Fix tests.
* Fix issue when running Router.onRouteChangeComplete
* Simplify state management.
* Make sure we don't dispose the last active page.
* Reload invalid pages detected with the client side ping.
* Improve the pinger code.
* Touch the first page to speed up the future rebuild times.
* Add Websockets based pinger.
* Revert "Add Websockets based pinger."
This reverts commit f706a49a3d886d0231259b7a1fded750ced2e48f.
* Do not send requests per every route change.
* Make sure we are completing the middleware request always.
* Make sure test pages are prebuilt.
