Programmer Humor

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All of IT in one image (lemmy.ml)

submitted 2 days ago by [email protected] to c/[email protected]

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[–] [email protected] 13 points 1 day ago (1 children)

The Javascript literal interpretation of NaN never fails to amuse me.

[–] [email protected] 4 points 1 day ago (1 children)

"a"+"b" -> "ab"
"a"-"b" -> NaN

[–] [email protected] 2 points 1 day ago (1 children)

Yeah:

parseInt("a") -> NoT a NuMbEr

[–] [email protected] 2 points 1 day ago

Sure, but the main issue here is that JS doesn't only auto cast to more generic but in both directions.

Maybe a better example is this:

"a" + 1 -> "a1"
"a" - 1 -> NaN

With + it casts to the more generic string type and then executes the overloaded + as a string concatenation.

But with - it doesn't throw an exception (e.g. something like "Method not implemented"), but instead casts to the more specific number type, and "a" becomes a NaN, and NaN - 1 becomes NaN as well.

There's no situation where "a" - "b" makes any sense or could be regarded as intentional, so it should just throw an error. String minus number also only makes sense in very specific cases (specifically, the string being a number), so also here I'd expect an error.

If the programmer really wants to subtract one number from another and one or both of them are of type string, then the programmer should convert to number manually, e.g. using parseInt("1") - parseInt("2").