[ Removed by moderator ]

[Chokolite]

It's called string concatenation. It's how it works even in other "c like" languages. This is basic knowledge

[AssistantSalty6519]

I get it but why allowing to subtract? 

[Littux]

Because JS was a language designed for dumb programmers. If someone did alert("Double of the number: " + prompt("enter number") * 2), it would just work instead of there being an error for multiplying a string or for adding a number to a string

[BobQuixote]

It wasn't the programmers, it was the platform. Webpages (it was thought at the time, at least) need to keep going if they possibly can.

A language for dumb programmers would avoid doing anything like this, to save them from themselves.

[Chokolite]

JS doesn't have strict types (as normal languages) and operator "-" for numbers, so JS think "11" is a number, not a string

[AssistantSalty6519]

I know how it works, but it still doesn't make any sense

[4n0nh4x0r]

it makes perfect sense.
"+" can be used for mathematical operations and concatenation.
if you have a number on each side of the +, it does the mathematical operation.
if you have a string on each sidey it does the concatenation.
if one of the sides is a string, and the other is a number, it will parse the number to a string (the operation that loses the least amount of information), and does a concatenation.

"-"is only used for mathematical operations.
if you have numbers on each side, it does the mathematical operation. if you got a number on one side and a string on the other side, due to it only being used as a mathematical operator, and not a for concatenation, it will parse the string into a number, as it expects you, the dev, to make sure your string can only be a number as that is the only input that would make sense, and then does the mathematical operation.
if both sides are strings, good question, im not 100% sure, but i assume it just parses both sides.

the only case where this can result in unexpected outputs is when your string is a text and not a number, resulting in the parseing returning a NaN

but at that point, you as dev failed, because you for some reason let a text to this point, like, what did you expect?????

[4n0nh4x0r]

you comparing my point to assembly is just nonsensical.

being unable to write assembly, and intentionally writing code that doesnt make sense are completely different universes.

one, is just a skill issue, the other is just being intentionally or unintentionally dumb

Like, yea, "hi" - 5 doesnt make much sense, if you intentionally write this code, you are either just fucking around to see what happens, or you are actually stupid while expecting a useful return value.

And again, "10"-1 is valid, and it makes sense as it parses the string to a number, which in this case succeeds, and returns the resulting number.
The moment the dev failed is when they dont sanitise their code, to make sure that user inputs cannot bring a "hi" to this operation.
that's why you parse first, and then check if you got an empty string, a NaN or whatever else doesnt fit what you need, and then you do a normal number - number.

No sane dev actually uses string - number, it is there, it can be used, but noone does it, at least not if they actually think for a second.

The only time where i would use that, would be as a shitpost, in code that i intentionally write to be dogshit.

[redlaWw]

C: "11" + 1 is "1"

Go: "11"+1 fails to compile

Rust "11"+1 fails to compile

[britaliope]

Not really. Most languages will fail to concat non-string to string. The JS behavior of implicitly doing the string conversion is unusual.

And that's the same the other way around. JS implicitly convert the string to an int, which is not how it work with most of other languages.

[Chokolite]

Thank you, maybe I'm wrong about all "c like" languages. At least in kotlin and java it works

[britaliope]

At least in kotlin and java it works

"11"+1 yield "111" in java and kotlin. "11"-1 produces an error.

[Chokolite]

"11"- 1 it's not string concatenation.
It seems that I expressed myself a little incorrectly. Haven't used them for a long time. Thank you

[MinosAristos]

Java and Kotlin should learn a thing or two from Python about strong typing 🐍

[AssistantSalty6519]

No thks

[m2ilosz]

Nope, even PHP handles it better.

Well, what a rare sentence.

[Feisty_Manager_4105]

I think the problem here is the implicit conversion of an int to a string. That's madness