Standard library translation

How Lua / Luau stdlib functions translate to TypeScript.

Error handling

local ok, err = pcall(function() risky() end)
if not ok then warn(err) end

const [ok, err] = pcall(() => { risky(); });
if (!ok) warn(err);

pcall, xpcall, and error are runtime helpers in native mode and pass through to the rbxts shims in rbxts mode.

Iteration

for k, v in pairs(t) do  ... end
for i, v in ipairs(arr) do  ... end

for (let k of pairKeys(t)) { const v = pairValue(t, k); ... }
for (let __i = 0; __i < arr.length; __i++) { const i = __i + 1; const v = arr[__i]; ... }

ipairs is fully inlined (no helper call). pairs uses the pairKeys / pairValue helpers so Instance-keyed tables work correctly with a host runtime.

Tables

Luau	TypeScript
table.insert(t, v)	table.insert(t, v) (helper)
table.remove(t, i)	table.remove(t, i) (helper)
table.concat(t, sep)	table.concat(t, sep) (helper)
#t	lualen(t)
t[k] (numeric k)	t[k - 1] (inlined) or luaIndex(t, k) (variable)

Strings

Luau	TypeScript
string.format("%d", n)	string.format("%d", n) (helper)
string.gsub(s, pat, rep)	string.gsub(s, pat, rep) (helper)
string.sub(s, i, j)	string.sub(s, i, j) (helper)
s1 .. s2	concat(s1, s2) (helper), handles Luau's coercion rules

Metatables

setmetatable(t, { __index = base })

setmetatable(t, { __index: base });

setmetatable and getmetatable are helpers. The metatable is stored on a hidden symbol, not as an enumerable own property.

Coroutines

coroutine.create, coroutine.resume, coroutine.yield, coroutine.wrap map to runtime helpers backed by generators. Note: only cooperative-yielding patterns survive; preemptive yielding doesn't work in JS.

task.wait, task.spawn, task.delay, task.defer come from the rbxts task service shim. Pair them with async / await.