Monitor `yarn.lock` to trigger reloads

[rauchg]

Not sure if we're ignoring it right now, but I've noticed that after running yarn, reloading is not triggered.

I think a smart shortcut to do that would be to detect yarn.lock having changed

[timneutkens]

@rauchg do you want to trigger a full process reload or a HMR?

[rauchg]

HMR. I suspect it should already trigger but maybe it doesn't ? Maybe cause it's non-js

[sedubois]

I think the same remark applies to next.config.js, changing it doesn't seem to trigger a reload.

[arunoda]

@sedubois I think we watch next.config.js and restart the webpack instance. We can't do HMR only for this because this might have core webpack config changes.

[sedubois]

@arunoda ok maybe, but as a user I don't see any message that changes in next.config.js are taken into account.

[timneutkens]

@arunoda @sedubois We do reload the server, also, it should show a message. https://github.com/zeit/next.js/blob/master/bin/next#L71-L81

Edit: just tested. It does show a message when reloading next.config.js

[sedubois]

@timneutkens I don't see that behaviour. When I change some text in next.config.js then hit save, Next doesn't give any message (such as WAIT Compiling...) in console.

Don't know if it matters, but I run with yarn dev where "dev": "nodemon -w server -w universal". Maybe the code you showed doesn't work with custom server.

[timneutkens]

It's using next indeed. For the custom server api you have to manage it yourself.

[sedubois]

OK, makes sense.

[rauchg]

New thought: yarn.lock deltas actually give us awesome information about what has changed, and we can invalidate the portions of the tree that are affected.

For example, if you have page b.js that depends on react-portal, and a dependency of react-portal changes, we would only schedule b.js for re-computation (specially in light of our upcoming re-factor to only re-compute what's currently being rendered upon source change

[timneutkens]

Looks like create-react-app does it this way: https://github.com/facebook/create-react-app/blob/next/packages/react-dev-utils/WatchMissingNodeModulesPlugin.js