"firebase serve" in firebase functions is not running the latest changes

Question

I am playing with firebase functions. Works fine when deploying to firebase server using command firebase deploy --only functions. However, I would like to test my functions locally before deploy to server of course. What I see running firebase serve is that the functions "deployed" locally have not the latest changes I did in indext.ts - are running the last builded version, which are in index.js.

My question is, How do I manual build my firebase functions project to test them locally with latest changes? Should firebase serve autobuild the project before deploy it locally? For me, it sounds like a bug.

Answer 1

firebase serve doesn't seem to be running npm build. But if you look inside functions/package.json, you can see there is already a serve script there that performs npm run build && firebase serve --only functions. So if you just do:

cd functions
npm run serve

You can build and serve without having to do two separate commands.

Answer 2

If you want to reload the changes to your TypeScript when running firebase serve or firebase functions:shell, all you have to do is build your project again using npm script that was created for you when you initialized the project (see package.json):

cd functions
npm run build

This will transpile your TypeScript to JavaScript, and the changes to the JavaScript will get picked up by the emulator automatically.

Also, if you are a more advanced TypeScript user, you can run tsc --watch to automatically compile TS to JS when source files change on disk. You can read more about that in this blog.