Divide by zero Typechecking

We have type literals for numbers already and a strictNullCheck compiler option – wouldn’t it be awesome if we had a type guard again divide-by-zero errors? I’m building a game that involved a lot of math, computing intersections of lines and such. But what if a line is parallel? It would be cool if the compiler would suggest this as a type error.

function f(): number | 0 {
    return 0
}

const y = 100 / f()

TypeScript Version: 2.7.0-dev.201xxxxx

[weswigham]

You can actually kinda already define an Infinity numeric literal type. Just make a type alias to a number that’s too big for JS to accurately represent and it’ll round to Infinity. The issue is that the global Infinity constant isn’t of this type 😉 , and declaration emit for this type may not work 😮 . It’s super hacky. We should really just add the NaN and Infinity numeric literal types (back). 🐱 Plus, NaN even has wonky comparability we should encode 😄

[RyanCavanaugh]

Since this produces Infinity (which is meaningful) instead of NaN it’s hard to even interpret it as an error. intersectDistance(ray1, ray2) returns Infinity when they’re parallel… not a problem?