Typescript Saved My Game's Performance



For quite awhile bulletz.io was written in vanilla javascript. The only libraries I used were RxJs and Phoenix Websockets. Performance was top notch for quite awhile due to the lack of framework, highly customized rendering code, and a specialized engine. I regularly got complements on the performance and smoothness of rendering.

Screenshot of bulletz.io

October 2019

Several comments came in via email, forums, and text message from friends commenting on the poor rendering performance of my game bulletz.io. The only changes I had made (from my perspective) were trivial and had nothing to do with rendering. I'd pretty much completely halted development at this point.

What happened?

My laptop broke last October. Due to this I got a spankin new Macbook. I re-installed all of my dependencies. Due to some bad development practices on my part (hobby project give me a break) I bumped the version of RxJs.

My new macbook pro

Why was this problematic? well...

RxJs ChangeLog

6.0.0-alpha.1 (2018-01-12)



schedulers: Scheduler instances have changed names to be suffixed with Scheduler, (e.g. asap -> asapScheduler)


The animationFrameScheduler was moved and I didn't notice. This was how I was controlling my rendering time. I was basically rendering all the time eating users' CPU cycles.

Late 2019

For fun I refactored bulletz.io to be written in Typescript.

To my surprise, typescript threw an exception indicating that rxjs exported no field named animationFrameScheduler from the location I waws importing it.

At this point - I wasn't even using typescript features yet. I had ONLY switched to the Typescript compiler and had set it up to check all of my javascript files.

I found countless other type errors littered throughout my garbage code base during my port to poorly written typescript.


I switched to using the real animationFrameScheduler and my games performance went back to how it used to be.

Typescript saved the game's performance.