Why would it be a joke? We've had compilers that compile from newer JS syntax to older JS syntax for years (not to mention all the compilers that compile from

Why would it be a joke? We've had compilers that compile from newer JS syntax to older JS syntax for years (not to mention all the compilers that compile from another language into JS). Traceur was the first reasonably well-known one I remember hearing about, then Babel came out and took over the ecosystem. Devs want to be able to use the latest JS syntax, but also have to target older browsers. Compiling new syntax to equivalent older syntax is a perfectly reasonable thing to do. Effectively all JS build tools have been written in JS, but this looks like an attempt to recreate some of that functionality in Rust. I'm curious how much of an actual perf difference there is in practice, given that Babel is usually just one part of the build pipeline.