Not really. (string[0] == string[0].toUpperCase() && string[0] != string[0].toLowerCase()) is the correct way to approach this problem. If toUpperCase() and toLowerCase() don't handle Turkish letters, then that's a BUG in those methods, which should be reported and someone should freaking take responsibility for them and fix them.

Adding another module with a method does not fix the original problem, it just creates more problems for other people to solve.

If "true" is not a valid answer, what would've been one? Similar code in C# returns the same. E.g. Console.WriteLine("שלום".ToUpperInvariant()=="שלום") returns true.

string[0] === string[0].toUpperCase() && string[0].toUpperCase() != string[0].toLowerCase();

That code fails in a whole host of cases, kind of proving that sometimes trivial "just one line" functions aren't actual that trivial to get right.

edit: fortunately there's an npm modules you can included to fix it...

Maybe F1axs knows that at this particular spot the string will never be empty? There are two philosophies in libraries; one is to check for every possible error in the lib function, the other is to state the pre-conditions in the documentation.

> Not that I agree with micro modules (I would rather see a set of js core libs)

Why not both? If you just want one part of a module, you can just import the dependency directly, if you want a whole core lib, you can do that.

Some people really like underscore and import that. I use ES6/7 functions for the most part, but underscore has some useful things I can import on their own.