But a compiler for what? Plain JS without any APIs? JS that uses the Node.js API? JS that uses the Web APIs? The problem with base JS is that it's a general purpose scripting language that lacks some of the basics that you need before you can compile the code as something that can "do a thing" on its own, without still needing an interpreter for the third party APIs the code tries to make use of that rely on out-of-language hooks (like Node.js)