LuaU Globals

Default globals

These are available in every rule script regardless of config.

json.encode(value: any) -> string

Serializes a Lua value to a JSON string. Tables with integer keys become JSON arrays. Tables with string keys become JSON objects. Mixed tables are not supported.

local s = json.encode({ source = "hello", inline = {} })
-- s = '{"source":"hello","inline":[]}'

json.decode(s: string) -> any

Parses a JSON string to a Lua value. Returns nil on parse error (does not raise).

local node = json.decode(input)
if not node then error("invalid input") end

Standard LuaU library

The following standard libraries are available:

Library	Notable functions
table	insert, remove, concat, sort, unpack
string	format, find, gmatch, gsub, sub, len, rep
math	floor, ceil, min, max, abs
Global	ipairs, pairs, tostring, tonumber, error, pcall, xpcall, type, select

Permission-gated globals

These are only available when the corresponding permission is declared in config.

http.get(url: string) -> string

Makes an outbound HTTP GET request to url. Returns the response body as a string. Raises a runtime error if url is not on the configured allowlist or if the request fails.

Requires:

permissions:
  http:
    allowlist:
      - "the-domain.com"

Absent globals

The following are explicitly not available:

• require / module loading
• io (file I/O)
• os (operating system access)
• debug (LuaU debug library)
• coroutine (coroutine support, may be added in a future version)