I do a lot of TypeScript these days. It's possible to define a type which equates to one or more literal string values. The TypeScript compiler will complain if

I do a lot of TypeScript these days. It's possible to define a type which equates to one or more literal string values. The TypeScript compiler will complain if you try and supply an invalid string parameter. So --at least for TypeScript-- I think this is less of a concern than in the past (and TypeScript is growing in popularity within the JS community). In a more general sense, I agree with the author that the 2nd code sample offers additional clarity.