The following is a list of functions and variables that are native to Lua.
These functions can be used in a standard installation of
[Lua 5.1.4](https://www.lua.org/manual/5.1/), though there are some
differences in how some of these work on Roblox.


Throws an error if the provided `value` is `false` or `nil`. If the
assertion passes, it returns all values passed to it.

```lua
local product = 90 * 4
assert(product == 360, "Oh dear, multiplication is broken")
-- The line above does nothing, because 90 times 4 is 360
```


assert

value

The value that will be asserted against.


errorMessage

The text that will be shown in the error if the assertion fails.


Throws an error if the provided `value` resolves to `false` or `nil`.


Performs an operation on the Lua garbage collector based on the specified
option.

Roblox's Lua sandbox only allows the "count" option to be used, so none of
the other standard options are available.

The "count" option returns the total memory in use by Lua (in kilobytes).


collectgarbage

operation

The name of the operation that should be performed by the garbage
collector.


Performs the specified operation of the garbage collector.


Terminates the last protected function called and outputs `message` as an
error message. If the function containing the error is not called in a
protected function such as `pcall()`, then the script which called the
function will terminate. The error function itself never returns and acts
like a script error.

The `level` argument specifies how to get the error position. With level
`1` (the default), the error position is where the error function was
called. Level 2 points the error to where the function that called error
was called; and so on. Passing a level `0` avoids the addition of error
position information to the message.


error

message

level

The level of information that should be printed. Defaults to 1.


Halts thread execution and throws an error.


Returns the current environment in use by the caller, as a dictionary.

- If provided with a function, the environment of the function will be
  returned.
- If provided with an integer, `getfenv()` will provide the environment of
  the function at the provided stack level: Level 1 is the function
  calling `getfenv()`. If `stack` is `0`, `getfenv()` returns the global
  environment of the current script. When using `getfenv()` to get the
  current environment of a script, it will return the same table every
  time within the specific thread.

```lua
-- Get the current environment

myVariable = "Hello, environments"  -- A global variable (non-local)
local env = getfenv()
print(env["myVariable"])  --> Hello, environments
```

```lua
-- Get the environment of a function

local function printMessage()
    print(message)
end
local env = getfenv(printMessage)
env.message = "Hello, function environments"
printMessage()  --> Hello, function environments
```

```lua
-- Get the environment based on stack

local function whatIsThePassword(password)
    local env = getfenv(1)  -- Get the environment 1 level up, or whatever called this function
    print(env.password)  -- Get the password from the environment one level up
    print(password)  --> nil
end

local function openSesame()
    local password = "secret"  -- A variable local to openSesame()
    whatIsThePassword(password)
end

openSesame()
```


getfenv

stack

The stack level (int) of the environment to be returned; or the
function whose environment will be returned.


Returns the current environment in use by the caller, as a dictionary.


Returns the metatable of the given table `t` if it has one, otherwise
returns nil. If `t` does have a metatable, and the `__metatable`
metamethod is set, it returns that value instead.

```lua
-- Demonstrate getmetatable:
local meta = {}
local t = setmetatable({}, meta)
print(getmetatable(t) == meta) --> true
-- Make the original metatable unrecoverable by setting the __metatable metamethod:
meta.__metatable = "protected"
print(getmetatable(t)) --> protected
```


getmetatable

Returns the metatable of the given table.


Returns three values: an iterator function, the table `t` and the number
`0`. Each time the iterator function is called, it returns the next
numerical index-value pair in the table. When used in a generic for-loop,
the return values can be used to iterate over each numerical index in the
table:

```lua
local fruits = {"apples", "oranges", "kiwi"}
for index, fruit in ipairs(fruits) do
   print(index, fruit) --> 1 apples, 2 oranges, 3 kiwi, etc...
end
```


ipairs

A table whose elements are to be iterated over.


Returns an iterator function and the table for use in a for loop.


Loads Lua code from a string, and returns it as a function.

Unlike standard Lua 5.1, Roblox's Lua cannot load the binary version of
Lua using loadstring.


loadstring

newproxy

addMetatable

Returns the first key/value pair in the array. If a `lastKey` argument was
specified then returns the next element in the array based on the key that
provided. The order in which the indices are enumerated is not specified,
even for numeric indices. To traverse a table in numeric order, use a
numerical for loop or `ipairs`.

The behavior of next is undefined if, during the traversal, you assign any
value to a non-existent field in the table. You may, however, modify
existing fields. In particular, you may clear existing fields.


lastKey

The last key that was previously retrieved from a call to next.


An iterator function for use in for loops.


Returns an iterator function, the passed table `t`, and `nil`, so that the
construction will iterate over all key/value pairs of that table when used
in a generic `for` loop:

```lua
local scores = {
    ["John"] = 5,
    ["Sally"] = 10
}

for name, score in pairs(scores) do
    print(name .. " has score: " .. score)
end
```


pairs

An array or dictionary table to iterate over.


Returns an iterator function and the provided table for use in a `for` loop.


Calls the function `func` with the given arguments in protected mode. This
means that any error inside `func` is not propagated; instead, `pcall()`
catches the error and returns a status code. Its first result is the
status code (a boolean), which is true if the call succeeds without
errors. In such case, `pcall()` also returns all results from the call,
after this first result. In case of any error, `pcall()` returns false
plus the error message.


pcall

func

The function to be called in protected mode.


args

The arguments to send to `func` when executing.


Runs the provided function and catches any error it throws, returning the
function's success and its results.


Receives any number of arguments, and prints their values to the output.
`print` is not intended for formatted output, but only as a quick way to
show a value, typically for debugging. For a formatted output, use
`Library.string.format()`. On Roblox, `print` does not call `tostring`,
but the `__tostring` metamethod still fires if the table has one.


print

params

Any number of arguments to be outputted.


Prints all provided values to the output.


Checks whether `v1` is equal to `v2`, without invoking any metamethod.


rawequal

Returns whether `v1` is equal to `v2`, bypassing their metamethods.


Gets the real value of `table[index]`, without invoking any metamethod.


rawget

index

Gets the real value of `table[index]`, bypassing any metamethods.


Sets the real value of `table[index]` to a given `value`, without invoking
any metamethod.


rawset

The index to set in `t` to a specified `value`. Must be different from
nil.


The value to be set to a specified `index` in table `t`.


Sets the real value of `table[index]`, bypassing any metamethods.


Returns all arguments after argument number `index`. If negative, it will
return from the end of the argument list.

```lua
print(select(2, "A", "B", "C")) --> B C
print(select(-1, "A", "B", "C")) --> C
```

Returns the total number of arguments that were passed after the `cmd`
argument, which must be `"#"` to use `select` in this fashion.

```lua
print(select("#", "A", "B", "C")) --> 3
```

If `cmd` is a number, the function will return all values after that
index.

```lua
print(select(2, "A", "B", "C")) --> B C
```


select

The index of the argument to return all arguments after in `args`. or
must be "#".


Returns all arguments after the given index.


Sets the environment to be used by the given function. `f` can be a
function or a number that specifies the function at that stack level:
Level 1 is the function calling `setfenv()`. `setfenv()` returns the given
function.

If `f` is ` 0``, then  `setfenv()` changes the environment of the running
thread and returns no values.


setfenv

Either a function or a number that specifies the function at that
stack level.


fenv

The function environment table to set for the specified function.


Sets the metatable for the given table `t` to `newMeta`. If `newMeta` is
nil, the metatable of `t` is removed. Finally, this function returns the
table `t` which was passed to it. If `t` already has a metatable whose
`__metatable` metamethod is set, calling this on `t` raises an error.

```lua
local meta = {__metatable = "protected"}
local t = {}
setmetatable(t, meta) -- This sets the metatable of t
-- We now have a table, t, with a metatable. If we try to change it...
setmetatable(t, {}) --> Error: cannot change a protected metatable
```


setmetatable

newMeta

If nil, the metatable of the given table `t` is removed. Otherwise,
the metatable to set for the given table `t`.


Attempts to convert the arg into a number with a specified base to
interpret the value in. If it cannot be converted, this function returns
nil.

The base may be any integer between 2 and 36, inclusive. In bases above
10, the letter 'A' (in either upper or lower case) represents 10, 'B'
represents 11, and so forth, with 'Z' representing 35. In base 10 (the
default), the number may have a decimal part, as well as an optional
exponent part. In other bases, only unsigned integers are accepted.

If a string begins with `0x` and a base is not provided, the `0x` is
trimmed and the base is assumed to be 16, or hexadecimal.

```lua
print(tonumber("1337")) --> 1337 (assumes base 10, decimal)
print(tonumber("1.25")) --> 1.25 (base 10 may have decimal portions)
print(tonumber("3e2")) --> 300 (base 10 may have exponent portion, 3 &times; 10 ^ 2)
print(tonumber("25", 8)) --> 21 (base 8, octal)
print(tonumber("0x100")) --> 256 (assumes base 16, hexadecimal)
print(tonumber("roblox")) --> nil (does not raise an error)
-- Tip: use with assert if you would like unconvertable numbers to raise an error
print(assert(tonumber("roblox"))) --> Error: assertion failed
```


tonumber

The object to be converted into a number.


base

The numerical base to convert _arg_ into.


Returns the provided value converted to a number, or nil if impossible.


Receives an argument of any type and converts it to a string in a
reasonable format. For complete control of how numbers are converted, use
string.format. If the metatable of `e` has a `__tostring` metamethod, then
it will be called with `e` as the only argument and will return the
result.

```lua
local isRobloxCool = true
-- Convert the boolean to a string then concatenate:
print("Roblox is cool: " .. tostring(isRobloxCool)) --> Roblox is cool: true
```


tostring

The object to be converted into a string.


Returns the provided value converted to a string, or nil if impossible.


Returns the type of its only argument, coded as a string. The possible
results of this function are "nil" (a string, not the value nil),
"number", "string", "boolean", "table", "vector", "function", "thread",
and "userdata".


type

Returns the basic type of the provided object.


Returns the elements from the given table. By default, _i_ is 1 and _j_ is
the length of _list_, as defined by the length operator.


unpack

list

Returns all elements from the given list as a tuple.


This function is similar to pcall, except that you can set a new error
handler.

`xpcall()` calls function `f` in protected mode, using `err` as the error
handler, and passes a list of arguments. Any error inside `f` is not
propagated; instead, `xpcall()` catches the error, calls the `err`
function with the original error object, and returns a status code. Its
first result is the status code (a boolean), which is true if the call
succeeds without errors. In this case, `xpcall()` also returns all results
from the call, after this first result. In case of any error, `xpcall()`
returns false plus the result from `err`.


xpcall

The function to be used as an error handle if xpcall catches an error.


Similar to `pcall()` except it uses a custom error handler.


Lua Globals

A table that is shared between all scripts of the same context level.


A global variable (not a function) that holds a string containing the
current interpreter version.


_VERSION

A global variable that holds a string containing the current interpreter
version.


A list of functions and variables that are native to Lua.


Default Value: {defaultValueStart}{defaultValueEnd}

This function returns immediately if possible, but can yield the thread that called it until it can return a value.

This member doesn’t appear in the object browser and is not intended for widespread use.

This member is only accessible only through the command bar. Attempting to access this member from scripts causes an error.

This function can’t pause the Lua thread that called it.

Attempting to access this member in scripts causes an error. You might be able to access this member from Roblox Studio's property window.

This member doesn’t appear in Roblox Studio’s Object Browser.

You can’t create an instance of this class with the Instance.new constructor.

Roblox does not replicate this member across its server-client boundary.

Lua code can’t access this member. You might be able to change its value from the property window in Roblox Studio.

This object’s replication behavior is dependent on the player who owns it.

This member is accessible only through the command bar and plugins only. Attempting to access this member from scripts causes an error.

This property is read-only and is safe to read in unsynchronized threads. Attempting to write to it causes an error.

This member is read only. Attempting to write to this member causes an error.

This member is accessible only in CoreScripts.

Only Roblox CoreScripts can access this member, and it isn’t usable by Players.

You can read and write to this property safely from multiple threads.

This class is a top-level singleton. Retrieve an instance of this class with the GetService function.

Multiple threads can potentially write to this property, so it’s unsafe to read from unsynchronized threads.

This function pauses the Lua thread that called it until it returns a result. This doesn’t interrupt other scripts.

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Lua Globals

Summary

Functions

Properties

Functions

assert

Parameters

Returns

collectgarbage

Parameters

Returns

error

Parameters

Returns

getfenv

Parameters

Returns

getmetatable

Parameters

Returns

ipairs

Parameters

Returns

loadstring

Parameters

Returns

newproxy

Parameters

Returns

next

Parameters

Returns

pairs

Parameters

Returns

pcall

Parameters

Returns

print

Parameters

Returns

rawequal

Parameters

Returns

rawget

Parameters

Returns

rawset

Parameters

Returns

select

Parameters

Returns

setfenv

Parameters

Returns

setmetatable

Parameters

Returns

tonumber

Parameters

Returns

tostring

Parameters

Returns

type

Parameters

Returns

unpack

Parameters

Returns

xpcall

Parameters

Returns

Properties

_G

_VERSION