Case-sensitive js sort

[JB712]

This is more of a comment than a problem.

The algorithm in JavaScript is case-sensitive (which means output will be ["a", "c", "B"] instead of ["a", "B", "c"].

A solution within the function could be at the very beginning of declaration:
function natcompare(a, b) { a = a?.toLowerCase(); b = b?.toLowerCase(); var ia = 0, ib = 0; ...

Or you have to call natcompare with lower-case text (natcompare(a..toLowerCase(), b.toLowerCase())

[sourcefrog]

I think the default should be case-sensitive, in part because that is the same as a<b.

Possibly we could add a case-insensitive version, although it seems pretty straightforward for the caller to squash them.