This is great to see! It's important to note that this isn't just yet another "X compiled to Y using Z", but a VM written from scratch natively in Javascript.
The result is a much smaller size, it's more understandable, hackable, extensible - all things that Lua's standard C implementation is great for. It's likely also easier to optimise this way.
I began on a similar project some years back, but as many spare-time projects go, never finished it: http://code.matthewwild.co.uk/ljs
No but seriously, if you want to write a VM in Javascript, I would suggest learning how to write a VM in a language more suited to writing a VM in. Maybe C or C++ then writing one in Javascript.
Do what you want. The nice thing about writing a managed language with GC in a managed language with GC, is that you don't have to write the GC. (Or the JIT, if you do it right.)
The result is a much smaller size, it's more understandable, hackable, extensible - all things that Lua's standard C implementation is great for. It's likely also easier to optimise this way.
I began on a similar project some years back, but as many spare-time projects go, never finished it: http://code.matthewwild.co.uk/ljs