> These are not things that would be caught by Typescript anyway. In my experience working with React, which is pretty heavily invested in typescript these day

> These are not things that would be caught by Typescript anyway. In my experience working with React, which is pretty heavily invested in typescript these days, if you go reasonably deep on doing typescript interfaces, it's like a switch gets flipped. A light dusting of typescript really does barely anything; it's just boilerplate. But once you get up to about 80-90% coverage, it's like a switch gets flipped. All of a sudden it's really, really good at detecting discrepancies - I had a thing I was working on today, where I had a cute little svg icon component in the giant SPA program we're writing - I was just reusing the thing, and attaching a click handler to it, and all of a sudden - this component we hadn't touched in months, typescript starts griping about it. And I'm like "oh come on, this is so basic - what the hell could be wrong about passing in a simple onclick handler?" Well - turns out nobody had ever needed to use the "event" param on that function, so it didn't even use one internally - what I was passing in, in plain JS, would have just been thrown away, because the internal 'passthrough' version of the function had no parameter at all. And I didn't notice it in light testing (we have TS set to emit our program even if it's failing tests). I tested the component, and because the behavior's invisible/internal, it seemed like it was probably fine. Maybe I would have caught it with really earnest, aggressive testing later, but I didn't even need to - typescript just nailed it instantly. I've had the privilege of working on some game development stuff outside of a web stack, and holy smokes does working in a complete, algebraically typed language change everything. When you go from 80-90% type coverage, to "hard 100%", it's just a complete 180°. It's just _freaky_ how good it is at catching errors. I'll change one little thing, and it can tell me "oh yeah - you know that cutscene an hour into the game? Yeah, you broke that." It's uncanny. It just absolutely changes everything about how I work.