Speeding up my TypeScript build

I was cleaning up my NPM modules on my side project. Since almost from the beginning, I have had 2 “child” package.json files, one for the backend and one for the frontend, and the “main” one in the project root.

It kind of made some sense from the keeping-things-tidy perspective: most of the modules needed on the backend will not be needed on the front-end. Just common sense, on the one hand. On the other hand, the simplicity of having one package.json was also attractive, so today, after a routine update of NPM packages, I gave it a try.

A quick tangent: Before updating the NPM packages, I checked the latest Node.js version: 14.2.0; nvm installed it, gave it a try, and after a 4 or 5 rounds of make clean build test I realized that it was 2 seconds faster than the 13.1.0, from 56s to 54s. Huh, OK, it’s not much, but if it’s an improvement, and it works, why not?! — let’s do it.

Now, back to the idea of consolidated package.json. I have copied all the things from the backend and frontend package.jsons, into the root one, and run the clean build: from the 54s it went to 61s. Ran it a few more time, same thing. Hm. That’s sad. After pondering a bit, I decided it’s not worth doing this change because it’s going to slow down my development builds by ~7% constantly. OK, at least I’ve learned something.

Now, if consolidating package.json files made the build slower, would having more of them, smaller, make it faster? — Let’s check! I moved some of the modules from the root to backend, and introduced a new package.json in frontend/tests — there were a few modules in the frontend package.json that were not needed for the “production” frontend code. Ran the clean build again, and, ta-da!! — it went from 54s to 50s. Ran it a few more times just to make sure, and yeah, it’s faster! 8-)

Interesting, isn’t it? Could it be related to my project being composite?