Introduction

roblox-ts is an attempt to bridge the abilities of TypeScript to work in a Roblox environment. We break down your code into an abstract syntax tree and emit functionally similar structures in Luau so that the code behaves the same.

Quick start & Documentation

Ready to dive in? Check out the documentation.

Performance tuning

The compileFiles write phase is async by default. On a fresh build of a ~2.6k-file workspace it drops from ~27s to ~6s on the default libuv pool (UV_THREADPOOL_SIZE=4) — roughly a 4–5× speedup with no configuration.

For an additional ~3–4× on large workspaces, bump the libuv thread pool before Node starts. Each pool thread reserves ~1 MiB of stack: UV_THREADPOOL_SIZE=32 adds ~32 MiB resident, =64 adds ~64 MiB. Returns diminish past 32. Setting process.env.UV_THREADPOOL_SIZE = "..." from inside JS has no effect — libuv reads the variable once at process init.

There is no single cross-shell invocation form. Use the one that matches your environment:

// package.json — recommended cross-platform form via `cross-env`
"scripts": {
    "build": "cross-env UV_THREADPOOL_SIZE=32 rbxtsc ..."
}

# POSIX (bash/zsh): inline assignment
UV_THREADPOOL_SIZE=32 rbxtsc ...

REM Windows cmd: set + && chain
set UV_THREADPOOL_SIZE=32&& rbxtsc ...

# PowerShell: $env: assignment + statement separator
$env:UV_THREADPOOL_SIZE=32; rbxtsc ...

Heads up: the bare POSIX VAR=value cmd form does not work in Windows cmd — UV_THREADPOOL_SIZE=32 rbxtsc ... silently produces a slower build there. Prefer cross-env in scripts that ship across machines.

If you want finer control, RBXTSC_WRITE_CONCURRENCY=N overrides the helper's drainer count directly (defaults to UV_THREADPOOL_SIZE × 2, capped at 256). Useful when tuning against a saturated disk or reproducing a serial baseline (RBXTSC_WRITE_CONCURRENCY=1).

Join the Community!

https://discord.roblox-ts.com

Games that use roblox-ts