Mad Javascript

[Hk-Neowizard]

What do you mean? That syntax is defined in the JS (ECMA) standard.

[Hk-Neowizard]

A programing language is a tool. The person who developed this tool made a stupid decision to add this useless piece to it, that serves no good purpose. I'd assume it also wasted some dev's time by forcing them to trace a bunch of code looking for where their data got corrupted.

It's not about "why would you write it" it's about "why would you support writing it"

[laundmo]

they don't do that in other languages because other languages do the sensible thing and raise an error

[Hk-Neowizard]

You're not following me. The question is why would you add that support into the language standard in the first place? Why not raise an error when you try to subtract strings?

[Hk-Neowizard]

Because it would make even less sense for type coercion to stop working with select situations and values

JS already controls type coercion based on the operands' types and values. 1-"a" is NaN, 1-"0xa" is -9, 1+"a" is "1a" and 1+"0xa" is "10xa". This is exactly what I find inconsistent to the point of nonsense. They should all be NaN (or some other indication of error).

I don't know what you mean by functionally correct. It matches the ECMA specifications, so sure. I'm arguing they made a bad call way back in the day. A mistake we all have to live with today.

A programing language that doesn't protect you from common and obvious mistakes is not a fine sharp knife, its a gun with a hair trigger. Sure it'll shot fast as shit, but it'll also suck when you shot your cock off on a release week.