>Rolling them by hand is awfully low-level, and completely defeats the point to using a high-level language. The problem is that you can't have "compiler/inter

>Rolling them by hand is awfully low-level, and completely defeats the point to using a high-level language. The problem is that you can't have "compiler/interpreter plugins" on the web, you have to use the language itself in order to extend it. This isn't React, Angular or even jQuery we're talking about, it's a library implementing a "fundamental" language feature that may be used tens of thousands of times in an app. This is why these kind of extremely low level optimizations matter for the makers of such a low-level library.