Fobos

Fobos is a Lua 5.1 to JavaScript transpiler, written in Lua 5.1.

Fobos is not finished. Don't rely on it for another few months at best.

Notice — Fobos is not designed to port existing Lua software to JavaScript. Its main purpose is to introduce Lua as a language for web development.

Feature parity

Missing features

• Standard library
• goto Lua 5.1 does not have a goto statement
• Global variables (oddly confusing to port?)
  • Use toplevel locals instead

Notes

• All Lua variables are prefixed with l$ to avoid collisions.
  • For JavaScript variables to be exposed to Lua code, they must be prefixed correctly.
• Tables cannot be indexed like JS objects.
  • Use the functions index_/newindex_ or rawget/rawset instead (the latter two will ignore metamethods).
  • JS Proxies can be used to wrap tables to make indexing more convenient.
• JS objects cannot be indexed like tables
  • To work around this, define helper JS functions for getting ((obj, key) => [obj[key]]) and setting ((obj, key, value) => [obj[key] = value]).
  • As with Proxies in JS, metamethods in Lua can be used to wrap objects.
• JS functions must return arrays to be used via Lua
  • This means functions must always return.
  • To return nil, use [] as a return value.

What Fobos can compile

• The classic OOP library (52 SLOC)

Post-ES5 features used

• Destructuring assignment (~2016)
• let/const (~2016)
• Arrow functions (~2015)
• Map (~2014)

License

zlib.