Emit Mode

tslua has two emit modes, controlled by the emitMode option in tsconfig.json or the --emitMode CLI flag.

{
  "tstl": {
    "emitMode": "optimized"
  }
}

"tstl" (default)

Matches TSTL’s Lua output as closely as possible. Use this when you need byte-for-byte compatibility with TSTL, or when comparing output between the two transpilers.

"optimized"

Emits cleaner Lua where tslua can prove the result is semantically equivalent. Every optimization preserves identical runtime behavior; the Lua evaluates to the same result as the default mode.

This mode is a work in progress. Current optimizations:

Area	Default (tstl)	Optimized	Notes
tostring() in concat	Wraps all non-string operands including numeric vars	Skips wrapping for numeric types	Lua .. handles numbers natively
C-style for loops	while loop with manual init/increment	for i = start, limit when pattern matches	Simpler, faster Lua
Map/Set for-of	Allocates intermediate tables	Zero-garbage stateless iteration via custom lualib helpers ↗	Less GC pressure

More optimizations will be added over time. If you find a case where optimized mode changes runtime behavior, please open an issue ↗.