IsA

Class checks understand common hierarchies (BasePart, Model, GuiObject, ValueBase, LuaSourceContainer, Tool, …).

Syntax

:IsA(className: string) -> boolean

Parameters

Parameter	Type	Description
`className`	`string`	The Roblox class name to match.

Returns

Type	Description
`boolean`	Boolean

Description

IsA is part of the Instances library. Instances are live proxies backed by game memory. Property reads and method calls go through Roblox's own objects.

The call is a predicate: it inspects the current state and returns a boolean without modifying anything.

The aliases :IsDescendantOf(ancestor) resolve to the same implementation.

Example

local part = workspace:FindFirstChildWhichIsA("BasePart")
if part then
    print(part:IsA("BasePart"), part:IsDescendantOf(workspace))
end

Notes

Aliases: :IsDescendantOf(ancestor).
Instance proxies are backed by live game memory.