> If you would start out with a JavaScript JIT (like V8) what things would you have to add (i.e. things that are not required to JIT JavaScript) besides the obv

> If you would start out with a JavaScript JIT (like V8) what things would you have to add (i.e. things that are not required to JIT JavaScript) besides the obvious modifications in the parser? This is such a tempting thought -- that JavaScript and Lua are similar enough languages that an engine for one could be retargeted to the other with some parser changes and a few new features. In practice it doesn't work out that way. Here is the story of Tessel, who originally set out to do it the other way around (implement JavaScript on LuaJIT) but reversed course after two years: https://tessel.io/blog/112888410737/moving-faster-with-iojs https://tessel.io/blog/112888410737/moving-faster-with-iojs "We believed that over time we could cover all of the corner cases of JavaScript with our own runtime, but perhaps we should have taken a cue from the “Wat talk” that it was going to be an uphill battle. While the semantics between JavaScript and Lua are very similar, they are also just slightly different in many ways (For example, the comparisons between null vs undefined vs falsy), and capturing all of those idiosyncrasies has proved frustrating for both the users and developers of the Runtime. [...] I still do believe it’s possible to make a nearly compatible runtime, but it’s going to take much more work than we expected and that resource investment would be an unwise business decision."