Oh, come on! I am in fact a front end developer. And when I saw the result first time a few years ago, I was surprised and wanted to use this “just JS”, but the reality was quite far from what I was expecting. It might look like JS, but if you check the source code of the app for the benchmark, you’ll realise that it looks more like C or C++.
More details in this thread: https://github.com/just-js/just/issues/5