The primary mechanism for reacting to debugger pauses. Set this to a
function that receives a `stopped` payload and returns a script resume
action dictionary indicating how execution should continue.

Only one `OnStopped` per `Class.DataModel` is allowed; it is not inherited
from the edit `Class.DataModel`.

If the callback returns nothing or throws,
`Enum.DebuggerResumeType.Resume` is assumed. Avoid modifying the
`Class.DataModel`, throwing unhandled errors, or calling async yielding
functions inside this callback.

#### Late-Set Behavior

If `OnStopped` is set while the `Class.DataModel` is already stopped at a
breakpoint and the previous value was `nil`, the callback runs
immediately.


ScriptDebuggerService.OnStopped

stopped

Dictionary describing why the debugger paused. The following key-value
pairs are valid:

- `Reason` — `Enum.ScriptStoppedReason` why the debugger paused.
- `ThreadIds` — Array of thread identifiers that stopped.
- `ExceptionText` — Error message present when `Reason` is
  `Enum.ScriptStoppedReason.Exception`.


Dictionary specifying how to resume execution. Contains the following
key-value pairs:

- `steppedType` — `Enum.DebuggerResumeType` describing how to resume.
- `threadId` — Number indicating which thread to step. Required for
  step actions.


The primary callback for reacting to debugger pauses. Returns a resume
action.


`ScriptDebuggerService` exposes the Roblox Studio Luau debugger for
programmatic use. It provides functionality for breakpoint management,
execution control, and runtime state inspection.

**APIs in this class are currently in beta and are subject to breaking
changes.**

#### Breakpoint Propagation

Breakpoints set in the **edit** `Class.DataModel` are set on the specific
script instance and do not propagate to clones, but they propagate to
corresponding scripts in play data models at the start of a playtest.
Breakpoints set in a **play** `Class.DataModel` propagate to script clones in
the same data model and to corresponding scripts in other data models.

#### Parallel Threads

The behavior of this API with parallel Luau is undefined.


Fires when a previously paused thread resumes. After this event, all
`frameId` values, `VariablesReference` values, and script variable objects
from that thread are invalidated. Re-fetch them the next time the
`Class.DataModel` stops if needed.

Avoid modifying the `Class.DataModel`, throwing unhandled errors, or
calling async yielding functions inside this event handler.


ScriptDebuggerService.Resumed

threadIds

An array of thread identifiers that resumed.


Fires when a previously paused thread resumes execution.


Adds a breakpoint to the specified script. If a breakpoint already exists
on the same script and line, its data is replaced with the new
configuration.

Errors if the script instance or breakpoint argument is invalid.


ScriptDebuggerService:AddBreakpoint

scriptInstance

The `Class.LuaSourceContainer` to place the breakpoint on.


breakpoint

Dictionary describing the breakpoint configuration through the
following key-value pairs:

- `Line` — Required 1-based line number.
- `Enabled` — Optional boolean whether the breakpoint is active.
  Default is `true`.
- `Condition` — Optional string indicating the Luau expression which
  must be truthy to pause, for example `"health < 10"`.
- `LogMessage` — Optional string message logged when the breakpoint is
  hit. This string is parsed as a comma-separated list of Luau
  expressions, evaluated in the breakpoint's scope, and concatenated
  `Global.LuaGlobals.print()`‑style with spaces between segments.
  String literals are quoted; bare identifiers reference live values.
  For example, `"'count is', count"` produces output like
  `count is 7`.
- `ContinueExecution` — If `true`, the `Class.DataModel` does not
  pause when the breakpoint is hit. Default is `false`.


Dictionary indicating whether the breakpoint was placed successfully
and on which line. Includes the following key-value pairs:

- `Verified` — Boolean value indicating whether the breakpoint was
  placed successfully.
- `Line` — The line number the breakpoint was placed on.
- `Message` — Optional explanation if `Verified` is `false`.


Adds a breakpoint to a script. If a breakpoint already exists on the same
script and line, its data is replaced.


Removes the breakpoint at the specified line in the given script. Returns
`false` if no breakpoint exists on the line (no-op). Errors if the script
instance or line number is invalid.


ScriptDebuggerService:RemoveBreakpoint

The `Class.LuaSourceContainer` containing the breakpoint.


line

The 1-based line number of the breakpoint to remove.


`true` if a breakpoint was removed, `false` if no breakpoint existed
on the line.


Removes the breakpoint on the given script and line.


Removes all breakpoints across all scripts.


ScriptDebuggerService:ClearBreakpoints

Sets the exception break mode on **all** `Class.DataModel|DataModels`. Use
`Enum.DebugBreakModeType` to specify when the debugger should pause on
exceptions.


ScriptDebuggerService:SetExceptionBreakMode

breakMode

Controls when the debugger pauses on exceptions.


Requests the debugger to pause at the next safe point. This method is
asynchronous and returns immediately. When the thread pauses,
`Class.ScriptDebuggerService.OnStopped|OnStopped` fires with reason
`Enum.ScriptStoppedReason.Pause`. Has no effect if already stopped.

Only meaningful when the `Class.DataModel` is running during a playtest.
Calling `Pause()` while already stopped at a breakpoint has no effect.


ScriptDebuggerService:Pause

Requests the debugger to pause at the next safe point.


Returns all paused Luau threads. Should be called when the
`Class.DataModel` is stopped (typically inside
`Class.ScriptDebuggerService.OnStopped|OnStopped`). Returns empty results
when the `Class.DataModel` is not stopped at a breakpoint or exception, or
when stopped via `Class.ScriptDebuggerService:Pause()|Pause()`.


ScriptDebuggerService:GetThreads

An array of script debug thread dictionaries, each containing the
following key-value pairs:

- `Id` — Numerical thread identifier; use with
  `Class.ScriptDebuggerService:GetStackTrace()|GetStackTrace()` and
  stepping.
- `Name` — Human-readable name of the script.


Returns the call stack for a paused thread, ordered innermost (current
execution point) to outermost. Use `startFrame` (1‑based) for paginated
retrieval of large stacks.

Errors if `threadId` or `startFrame` is invalid.


ScriptDebuggerService:GetStackTrace

threadId

The thread identifier from a script debug thread `Id` field (see
`Class.ScriptDebuggerService:GetThreads()|GetThreads()`).


startFrame

Optional 1-based frame index for paginated retrieval.


Dictionary containing the frames ordered innermost (current) to
outermost. Contains the following key-value pairs:

- `Frames` — Array of debug stack frame dictionaries. Each dictionary
  item contains the following key-value pairs:
  - `Id` — Numerical frame identifier; use with
    `Class.ScriptDebuggerService:GetRootVariables()|GetRootVariables()`
    and `Class.ScriptDebuggerService:Evaluate()|Evaluate()`.
  - `Name` — Human-readable name of the function at this frame.
  - `ScriptPath` — Full instance path of the script, for example
    `"ServerScriptService.MainScript"`.
  - `Line` — 1-based line number where execution is paused at this
    frame.
- `TotalFrames` — Total frame count, provided when paginating.


Returns the call stack for a paused thread.


Returns the root variables (locals, upvalues, globals) for the specified
stack frame. Each variable includes a `VariablesReference` field; if
greater than `0`, pass it to
`Class.ScriptDebuggerService:GetVariables()|GetVariables()` to drill into
children.

Errors if `frameId` is invalid. Returns empty if the `Class.DataModel` is
not stopped at a breakpoint or exception, or when stopped via
`Class.ScriptDebuggerService:Pause()|Pause()`.


ScriptDebuggerService:GetRootVariables

frameId

The frame identifier from a debug stack frame `Id` field (see
`Class.ScriptDebuggerService:GetStackTrace()|GetStackTrace()`).


An array of script variable dictionaries, each containing the
following key-value pairs:

- `Name` — String value indicating the variable name or table key.
- `Value` — String representation of the value.
- `Type` — String indicating the Luau type (`"number"`, `"string"`,
  `"table"`, `"Instance"`, etc.).
- `Scope` — `Enum.ScriptVariableScope` value (children inherit
  parent's scope).
- `VariablesReference` — If greater than `0`, call
  `Class.ScriptDebuggerService:GetVariables()|GetVariables()` with
  this to get children.


Returns the root variables (locals, upvalues, globals) for a stack frame.


Drills into structured variables such as tables and
`Class.Instance|Instances`. Pass a `VariablesReference` obtained from a
script variable returned by
`Class.ScriptDebuggerService:GetRootVariables()|GetRootVariables()` or a
previous call to this method.


ScriptDebuggerService:GetVariables

variablesReference

A reference from a previous script variable's `VariablesReference`
field (see
`Class.ScriptDebuggerService:GetRootVariables()|GetRootVariables()`).


An array of script variable dictionaries representing the children in
the same format as variable dictionaries from
`Class.ScriptDebuggerService:GetRootVariables()|GetRootVariables()`.
Returns empty if the `Class.DataModel` is not stopped at a breakpoint
or exception, or when stopped via
`Class.ScriptDebuggerService:Pause()|Pause()`.


Drills into structured variables (tables, `Class.Instance|Instances`).


Evaluates a Luau expression in the context of the specified stack frame,
or globally if no `frameId` is provided.

Errors if the expression has a syntax error or `frameId` is invalid.


ScriptDebuggerService:Evaluate

expression

Optional frame identifier. If omitted, evaluates globally.


Dictionary with the following key-value pairs:

- `Result` — String representation of the evaluated result.
- `Type` — String indicating the Luau type of the result (`"number"`,
  `"string"`, `"table"`, `"Instance"`, etc.).
- `VariablesReference` — If greater than `0`, drill into with
  `Class.ScriptDebuggerService:GetVariables()|GetVariables()`.


Evaluates a Luau expression in a stack frame's context.


ScriptDebuggerService

Provides programmatic breakpoint management, execution control, and runtime
inspection of Luau scripts during a playtest.


`Instance` is the base class for all classes in the Roblox class hierarchy
which can be part of the `Class.DataModel` tree.

It is not possible to directly create root `Instance` objects, but the special
`Datatype.Instance.new()` constructor creates objects via code, taking the
name of the class as a parameter and returning the created object.


Demonstrates detecting changes to an instance's ancestry by connecting to the
`Class.Instance.AncestryChanged` event.

The ChangingPart's Parent is set to different values overtime. The parent of
the part is the part's ancestor, so the `Class.Instance.AncestryChanged` event
will fire whenever it changes.


Fires when this instance is reparented or when any of its ancestors is
reparented.

You can use this event to track the deletion of an instance in Studio,
such as manual deletion in the Explorer or through a plugin. If you need
to detect when an instance is destroyed using `Class.Instance:Destroy()`,
use the `Class.Instance.Destroying` event instead.


Instance.AncestryChanged

child

The instance whose `Class.Instance.Parent|Parent` property changed,
which can be this instance or a more distant ancestor, **not**
necessarily the instance the handler is connected to.


parent

The new parent of the `child` parameter.


Fires when the `Class.Instance.Parent` property of this object or one of
its ancestors is changed.


This event fires whenever any attribute is changed on the instance,
including when an attribute is set to `nil`. The name of the changed
attribute is passed to the connected function.

For example, the following code snippet connects the `attributeChanged()`
function to fire whenever one of the part's attributes changes:

```lua
local Workspace = game:GetService("Workspace")

local part = Workspace.Part

local function attributeChanged(attributeName)
	print(attributeName, "changed")
end

part.AttributeChanged:Connect(attributeChanged)
```

See also `Class.Instance:GetAttributeChangedSignal()` which returns an
event that fires when a specific given attribute changes.


Instance.AttributeChanged

attribute

The name of the attribute that has been changed.


Fires whenever an attribute is changed on the `Class.Instance`.


This snippet prints the names of objects as they are added to the Workspace:


Fires after an object is parented to this `Class.Instance`.

Note, when using this method on a client to detect objects created by the
server it is necessary to use `Class.Instance:WaitForChild()` when
indexing these object's descendants. This is because the object and its
descendants are not guaranteed to replicate from the server to the client
simultaneously. For example:

```
local Workspace = game:GetService("Workspace")

Workspace.ChildAdded:Connect(function(child)
	-- Use WaitForChild() since descendants may not have replicated yet
	local head = child:WaitForChild("Head")
end)
```

Note, this event only operates for immediate children of the
`Class.Instance`. For an event that captures all descendants, use
`Class.Instance.DescendantAdded`.

See also `Class.Instance.ChildRemoved`.


Instance.ChildAdded

The `Class.Instance` that has been added.


Fires after an object is parented to this `Class.Instance`.


Instance.childAdded

This snippet prints the names of objects as they are removed from the
Workspace:


Fires after a child is removed from this `Class.Instance`.

Removed refers to when an object's parent is changed from this
`Class.Instance` to something other than this `Class.Instance`. Note, this
event will also fire when a child is destroyed (using
`Class.Instance:Destroy()`) as the destroy function sets an object's
parent to `nil`.

This event only operates for immediate children of the `Class.Instance`.
For an event that captures all descendants, use
`Class.Instance.DescendantRemoving`.

See also `Class.Instance.ChildAdded`.


Instance.ChildRemoved

The `Class.Instance` that has been removed.


Fires after a child is removed from this `Class.Instance`.


This following example will print the name of any object that is added to the
Workspace:


This event fires after a descendant is added to the `Class.Instance`.

As it fires for every descendant, parenting an object to the
`Class.Instance` will fire the event for this object and all of its
descendants individually.

If you're only concerned with the **direct children** of the
`Class.Instance`, use `Class.Instance.ChildAdded` instead.

See also `Class.Instance.DescendantRemoving`.


Instance.DescendantAdded

descendant

Fires after a descendant is added to the `Class.Instance`.


The following example prints the name of any descendant as it is being removed
from the Workspace:


This event fires **immediately before** the parent `Class.Instance`
changes such that a **descendant** instance will no longer be a
descendant. `Class.Instance:Destroy()|Destroy()` changes an instance's
`Class.Instance.Parent|Parent` to `nil`, so calling that method on a
descendant of the parent will cause this event to fire.

Since this event fires **before** the descendant's removal, the parent of
the descendant will be unchanged at the time of this event firing. If the
descendant is also a **direct child** of the parent, this event will fire
before `Class.Instance.ChildRemoved`.

If a descendant has children, this event fires with the descendant first,
followed by its descendants.

#### Warning

This event fires with the descendant object that is being removed.
Attempting to set the `Class.Instance.Parent|Parent` of the descendant to
something else will fail. Below is an example that demonstrates this:

```
local Workspace = game:GetService("Workspace")

Workspace.DescendantRemoving:Connect(function(descendant)
	-- Do not manipulate the parent of the descendant in this function!
	-- This event fires BECAUSE the parent was manipulated, and the change hasn't happened yet
	-- Therefore, it is problematic to change the parent like this:
	descendant.Parent = game
end)

local part = Instance.new("Part")
part.Parent = Workspace
part.Parent = nil
```

See also `Class.Instance.DescendantAdded|DescendantAdded`.


Instance.DescendantRemoving

The `Class.Instance` that is being removed.


Fires immediately before a descendant of the `Class.Instance` is removed.


This sample demonstrates how, when using Immediate signal behavior, an
Instance being destroyed remains in place until the connected function yields.


This sample demonstrates how, when using Deferred signal behavior, an Instance
is destroyed before the signal fires.


The `Class.Instance` will never be deleted from memory while a connected
function is still using it. However, if the function yields at any point,
the `Class.Instance` and its descendants will be parented to `nil`.

If the `Class.Workspace.SignalBehavior` property is set to
`Enum.SignalBehavior.Immediate`, this event fires immediately before the
`Class.Instance` or one of its ancestors is destroyed with
`Class.Instance:Destroy()`.

If the `Class.Workspace.SignalBehavior` property is set to
`Enum.SignalBehavior.Deferred`, this event fires at the next resumption
point, which will be after the `Class.Instance` or one of its ancestors is
destroyed with `Class.Instance:Destroy()`.

With `Enum.SignalBehavior.Deferred|Deferred` behavior, connecting a script
to its own `Class.Instance.Destroying` event is problematic, as the script
will be destroyed before the callback can be called (meaning it will not
execute).

When deleting an `Class.Instance` in Studio, such as manually deleting
through the [Explorer](/studio/explorer) or through a plugin,
the `Class.Instance` isn't destroyed. Instead, the parent is set to `nil`
which you can track with `Class.Instance.AncestryChanged`.


Instance.Destroying

Fires immediately before (or is deferred until after) the instance is
destroyed via `Class.Instance:Destroy()`.


This event fires whenever any style property is changed on the instance,
including when a property is set to `nil`.

```lua
local Players = game:GetService("Players")

local player = Players.LocalPlayer
local playerGui = player.PlayerGui
local HUDContainer = playerGui:WaitForChild("HUDContainer")
local meterBar = HUDContainer.MeterBar

local function stylePropertyChanged()
	print("Styled properties changed")
end

meterBar:StyledPropertiesChanged():Connect(stylePropertyChanged)
```


Instance.StyledPropertiesChanged

Fires whenever any style property is changed on the instance, including
when a property is set to `nil`.


This method applies a tag to the instance, with no effect if the tag is
already applied. Successfully adding a tag will fire a signal created by
`Class.CollectionService:GetInstanceAddedSignal()` with the given tag.

#### Warnings

- An instance's tags that were added client-side will be dropped if the
  server later adds or removes a tag on that instance because the server
  replicates all tags together and overwrites previous tags.

- When tagging an instance, it is common that some resources are used to
  give the tag its functionality, for example event connections or tables.
  To prevent memory leaks, it's a good idea to clean these up (disconnect,
  set to `nil`, etc.) when no longer needed for a tag. Do this when
  calling `Class.Instance:RemoveTag()`, calling
  `Class.Instance:Destroy()`, or in a function connected to a signal
  returned by `Class.CollectionService:GetInstanceRemovedSignal()`.


Instance:AddTag

The children function returns an array of the object's children.


Instance:children

Returns an array of the object's children.


This method destroys all of an instance's children and descendants.

```
local part = Instance.new("Part")

-- Add some sparkles
for i = 1, 3 do
	local sparkles = Instance.new("Sparkles")
	sparkles.Parent = part

  local sc = Instance.new("Sparkles")
  sc.Parent = sparkles
end

print("Children:", #part:GetChildren())  --> Children: 3

part:ClearAllChildren()

print("Children:", #part:GetChildren())  --> Children: 0
```

If you do not wish to destroy **all** children and descendants, use either
`Class.Instance:GetChildren()` or `Class.Instance:GetDescendants()` to
loop through those children/descendants and select what to destroy. For
example, the following code sample will destroy all
`Class.BasePart|BaseParts` descending from a `Class.Model`:

```
local Workspace = game:GetService("Workspace")

local model = Workspace:FindFirstChild("TestModel")

for _, descendant in model:GetDescendants() do
	if descendant:IsA("BasePart") then
		descendant:Destroy()
	end
end
```


Instance:ClearAllChildren

This method destroys all of an instance's children.


Demonstrates cloning a model using `Class.Instance:Clone()`.


`Clone()` creates a copy of an instance and all of its descendants,
ignoring all instances that are not
`Class.Instance.Archivable|Archivable`. The copy of the root instance is
returned by this method and its `Class.Instance.Parent|Parent` is set to
`nil`. Note that if the instance itself has
`Class.Instance.Archivable|Archivable` set to `false`, this method will
return `nil`.

If a reference property such as `Class.ObjectValue.Value` is set in a
cloned instance, the value of the copy's property depends on the
original's value:

- If a reference property refers to an instance that was **also** cloned,
  the copy will refer to the copy.
- If a reference property refers to an instance that was **not** cloned,
  the same value is maintained in the copy.


Instance:Clone

Create a copy of an instance and all its descendants, ignoring instances
that are not `Class.Instance.Archivable|Archivable`.


Instance:clone

Demonstrates destroying a Part using the `Class.Instance:Destroy()` function.

This function is the correct way to dispose of objects that are no longer
required.


Sets the `Class.Instance.Parent` property to `nil`, locks the
`Class.Instance.Parent` property, disconnects all connections, and calls
`Destroy()` on all children. This method is the correct way to dispose of
objects that are no longer required.

Disposing of unneeded objects is important, since unnecessary objects and
connections in a place use up memory which can lead to serious performance
issues over time.

As a best practice after calling `Destroy()` on an object, set any
variables referencing the object (or its descendants) to `nil`. This
prevents your code from accessing anything to do with the object.

```lua
local part = Instance.new("Part")
part.Name = "Hello, world"
part:Destroy()
-- Don't do this:
print(part.Name)  --> "Hello, world"
-- Do this to prevent the above line from working:
part = nil
```

Once an `Class.Instance` has been destroyed by this method, it cannot be
reused because the `Class.Instance.Parent` property is locked. To
**temporarily** remove an object instead of destroying it, set
`Class.Instance.Parent|Parent` to `nil`. For example:

```
local Workspace = game:GetService("Workspace")

object.Parent = nil
task.wait(2)
object.Parent = Workspace
```

To destroy an object after a set amount of time, use
`Class.Debris:AddItem()`.


Instance:Destroy

Sets the `Class.Instance.Parent` property to `nil`, locks the
`Class.Instance.Parent` property, disconnects all connections, and calls
`Destroy()` on all children.


Instance:destroy

Returns the first ancestor of the `Class.Instance` whose
`Class.Instance.Name` is equal to the given name.

This method works upwards, meaning it starts at the instance's immediate
`Class.Instance.Parent` and works up towards the `Class.DataModel`. If no
matching ancestor is found, it returns `nil`.

The following code snippet would find the first ancestor of the object
named `Car`.

```
local car = object:FindFirstAncestor("Car")
```

For variants of this method that find ancestors of a specific class,
please see `Class.Instance:FindFirstAncestorOfClass()` and
`Class.Instance:FindFirstAncestorWhichIsA()`.


Instance:FindFirstAncestor

name

The `Class.Instance.Name` to be looked for.


Returns the first ancestor of the `Class.Instance` whose
`Class.Instance.Name` is equal to the given name.


Returns the first ancestor of the `Class.Instance` whose
`Class.Object.ClassName` is equal to the given className.

This method works upwards, meaning it starts at the instance's immediate
`Class.Instance.Parent` and works up towards the `Class.DataModel`. If no
matching ancestor is found, it returns `nil`.

A common use of this method is finding the `Class.Model` a
`Class.BasePart` belongs to. For example:

```
local model = part:FindFirstAncestorOfClass("Model")
```

This method is a variant of `Class.Instance:FindFirstAncestor()` which
checks the `Class.Object.ClassName` property rather than
`Class.Instance.Name`. `Class.Instance:FindFirstAncestorWhichIsA()` also
exists, using the `Class.Object:IsA()` method instead to respect class
inheritance.


Instance:FindFirstAncestorOfClass

className

The `Class.Object.ClassName` to be looked for.


Returns the first ancestor of the `Class.Instance` whose
`Class.Object.ClassName` is equal to the given className.


Returns the first ancestor of the `Class.Instance` for whom
`Class.Object:IsA()` returns true for the given className.

This method works upwards, meaning it starts at the instance's immediate
`Class.Instance.Parent` and works up towards the `Class.DataModel`. If no
matching ancestor is found, it returns `nil`.

Unlike `Class.Instance:FindFirstAncestorOfClass()`, this method uses
`Class.Object:IsA()` which respects class inheritance. For example:

```
print(part:IsA("Part"))  --> true
print(part:IsA("BasePart"))  --> true
print(part:IsA("Instance"))  --> true
```

Therefore, the following code sample will return the first
`Class.BasePart` ancestor, regardless of if it is a `Class.WedgePart`,
`Class.MeshPart` or `Class.Part`.

```
local part = object:FindFirstAncestorWhichIsA("BasePart")
```

See also `Class.Instance:FindFirstAncestor()`.


Instance:FindFirstAncestorWhichIsA

Returns the first ancestor of the `Class.Instance` for whom
`Class.Object:IsA()` returns true for the given className.


The below would look in Workspace for an object name "Brick". If found, it
will change the name of the object to "Foo".


Returns the first child of the `Class.Instance` with the given name, or
`nil` if no such child exists. If the optional `recursive` argument is
`true`, this method searches all descendants rather than only the
immediate children of the `Class.Instance`.

#### Checking the Existence of an Object

`FindFirstChild()` is necessary if you need to verify an object exists
before continuing. Attempting to index a child by name using the dot
operator throws an error if the child doesn't exist.

```lua
local Workspace = game:GetService("Workspace")

-- The following line errors if the part doesn't exist in the workspace
Workspace.Part.Transparency = 0.5
```

A better approach is to use `FindFirstChild()` to first check for `Part`,
then use an `if` statement to run code that needs it.

```lua
local Workspace = game:GetService("Workspace")

local part = Workspace:FindFirstChild("Part")
if part then
	part.Transparency = 0.5
end
```

#### Finding a Child Whose Name Matches a Property

Sometimes the `Class.Instance.Name|Name` of an object is the same as that
of a property of its `Class.Instance.Parent|Parent`. When using the dot
operator, properties take precedence over children if they share a name.

In the following example, a `Class.Folder` called `Color` is added to a
`Class.Part`, which also has the `Class.Part.Color` property. Notice that
`part.Color` refers to the `Datatype.Color3` property value, not the child
`Class.Folder` instance. A benefit of using
`Class.Instance:FindFirstChild()|FindFirstChild()` is that the
introduction of new properties does not impose a risk on your code.

```lua
local part = Instance.new("Part")
local folder = Instance.new("Folder")
folder.Name = "Color"
folder.Parent = part
local c1 = part.Color  -- The property
local c2 = part:FindFirstChild("Color")  -- The child folder
```

#### Performance Notes

`Class.Instance:FindFirstChild()|FindFirstChild()` takes about 20% longer
than using the dot operator and almost 8 times longer than simply storing
a reference to an object. Therefore, you should avoid calling it in
performance-dependent code such as in tight loops or functions connected
to `Class.RunService.Heartbeat` and `Class.RunService.PreRender`. Instead,
store the result in a variable, or consider using
`Class.Instance.ChildAdded|ChildAdded` or
`Class.Instance:WaitForChild()|WaitForChild()` to detect when a child of a
given name becomes available.


Instance:FindFirstChild

The `Class.Instance.Name` to be searched for.


recursive

Whether or not the search should be conducted recursively.


Returns the first child of the `Class.Instance` found with the given name.


Instance:findFirstChild

Returns the first child of the `Class.Instance` whose
`Class.Object.ClassName|ClassName` is equal to the given `className`.
Unlike `Class.Instance:FindFirstChildWhichIsA()`, this method only returns
objects whose class matches `className`, ignoring class inheritance. If no
matching child is found, this method returns `nil`.


Instance:FindFirstChildOfClass

Returns the first child of the `Class.Instance` whose
`Class.Object.ClassName|ClassName` is equal to the given class name.


Returns the first child of the `Class.Instance` for whom
`Class.Object:IsA()` returns true for the given className.

If no matching child is found, this method returns `nil`. If the optional
recursive argument is true, this method searches all descendants rather
than only the immediate children of the `Class.Instance`.

Unlike `Class.Instance:FindFirstChildOfClass()`, this method uses
`Class.Object:IsA()` which respects class inheritance. For example:

```lua
print(part:IsA("Part")) --> true
print(part:IsA("BasePart")) --> true
print(part:IsA("Instance")) --> true
```

Therefore, the following code sample will return the first
`Class.BasePart` child, regardless of if it is a `Class.WedgePart`,
`Class.MeshPart` or `Class.Part`.

```
local part = object:FindFirstChildWhichIsA("BasePart")
```

Developers looking for a child by name, should use
`Class.Instance:FindFirstChild()` instead.


Instance:FindFirstChildWhichIsA

The `Class.Object.ClassName` to be searched for.


Returns the first child of the `Class.Instance` for whom
`Class.Object:IsA()` returns true for the given className.


Returns the first descendant found with the given `Class.Instance.Name`.

This method is disabled and cannot be used. To find the first descendant
of an instance, consider using the `recursive` parameter on
`Class.Instance:FindFirstChild()` instead.


Instance:FindFirstDescendant

The `Class.Instance.Name` to search for.


Returns the first descendant found with the given `Class.Instance.Name`.


If the `Class.Instance` is an `Class.Actor`, the `Class.Actor` itself is
returned. Otherwise, its closest ancestor `Class.Actor` is returned. If no
ancestor is an `Class.Actor`, the result is `nil`.


Instance:GetActor

Returns the `Class.Actor` associated with the Instance, if any.


This method returns the value which has been assigned to the given
attribute name. If no attribute has been assigned, `nil` is returned.

For example, the following code snippet sets and then gets the value of
the instance's `InitialPosition` attribute:

```lua
local Workspace = game:GetService("Workspace")

local part = Workspace.Part
part:SetAttribute("InitialPosition", part.Position)

local initialPosition = instance:GetAttribute("InitialPosition")
print(initialPosition)
```

#### See Also

- `Class.Instance:SetAttribute()` which sets the attribute with the given
  name to the given value.
- `Class.Instance:GetAttributes()` which returns a dictionary of key‑value
  pairs for each of the instance's attributes.


Instance:GetAttribute

The name of the attribute being retrieved.


The value which has been assigned to the given attribute name. If no
attribute has been assigned, `nil` is returned.


Returns the value which has been assigned to the given attribute name.


This method returns an event that behaves exactly like the
`Class.Object.Changed|Changed` event, except that it only fires when the
specific given attribute changes; effectively it is similar to
`Class.Object:GetPropertyChangedSignal()|GetPropertyChangedSignal()` but
for attributes.

It's generally a good idea to use this method instead of a connection to
`Class.Object.Changed|Changed` with a function that checks the attribute
name. Subsequent calls to this method on the same object with the same
attribute name return the same event.

The following code example returns a signal that fires the function
`attributeChanged()` when the part's `InitialPosition` attribute changes:

```lua
local Workspace = game:GetService("Workspace")

local part = Workspace.Part
part:SetAttribute("InitialPosition", part.Position)

local function attributeChanged()
	print("Attribute changed")
end

part:GetAttributeChangedSignal("InitialPosition"):Connect(attributeChanged)
```

See also `Class.Instance.AttributeChanged` which fires whenever any
attribute is changed on the instance.


Instance:GetAttributeChangedSignal

The name of the specified attribute for which the change signal is
being returned.


An event that fires when the given attribute changes.


Returns an event that fires when the given attribute changes.


This method returns a dictionary of key‑value pairs for each attribute
where the key is the attribute's name and the value is a non‑`nil` value.

For example, the following code snippet outputs an instance's attributes
and values:

```lua
local Workspace = game:GetService("Workspace")

local part = Workspace.Part
part:SetAttribute("InitialPosition", part.Position)
part:SetAttribute("CanUse", true)

for name, value in part:GetAttributes() do
	print(name .. " = " .. value)
end
```

See also `Class.Instance:GetAttribute()` which returns the value that has
been assigned to the given attribute name.


Instance:GetAttributes

A dictionary of string → variant pairs for each attribute where the
string is the name of the attribute and the variant is a non-nil
value.


Returns a dictionary of the instance's attributes.


The below would print the name of all objects currently in Workspace when ran.


Returns an array (a numerically indexed table) containing all of the
instance's direct children, or every `Class.Instance` whose
`Class.Instance.Parent|Parent` is equal to the object. The array can be
iterated upon using either a numeric or generic `for` loop:

```lua
local Workspace = game:GetService("Workspace")

-- Numeric loop example
local children = Workspace:GetChildren()
for i = 1, #children do
	local child = children[i]
	print(child.Name .. " is child number " .. i)
end
```

```lua
local Workspace = game:GetService("Workspace")

-- Generic loop example
local children = Workspace:GetChildren()
for i, child in children do
	print(child.Name .. " is child number " .. i)
end
```

Note that the returned array is **not** sorted in any particular order, so
manual sorting (for example using `Library.table.sort()`) is advised for
sorting the children returned by this method.

See also the `Class.Instance:GetDescendants()|GetDescendants()` method.


Instance:GetChildren

An array containing the instance's children.


Returns an array containing all of the instance's children.


Instance:getChildren

Returns a coded string of the debug ID used internally by Roblox. Note
that:

- This item is protected. Attempting to use it in a `Class.Script` or
  `Class.LocalScript` will cause an error.
- A debug ID is an ID used in debugging processes. It allows a debugger to
  read each instruction before an application processes it. All objects in
  Roblox act like processes and each run instructions (or 'code') that can
  be debugged if needed.
- This can be helpful for plugins which need to distinguish similar
  objects from one-another (such as objects that share the same name).


Instance:GetDebugId

scopeLength

Returns a coded string of the debug ID used internally by Roblox.


GetDescendants is often used to do something to all the descendants that are a
particular type of object. The code in this example uses GetDescendants and
`Class.Instance:IsA()` to find all of the parts in the workspace and turns
them green.


This object method returns an array that contains all of the descendants
of that object. Unlike `Class.Instance:GetChildren()`, which only returns
the immediate children of an object, this method finds every child of the
object, every child of those children, and so on.

Note that the returned array is **not** sorted in any particular order, so
manual sorting (for example using `Library.table.sort()`) is advised for
sorting the descendants returned by this method. Also consdier the
`Class.Instance:QueryDescendants()|QueryDescendants()` method to query
descendants by a combination of selectors and combinators.


Instance:GetDescendants

An array containing the instance's descendants.


Returns an array containing all of the descendants of the instance.


This code sample demonstrates the behavior of `Class.Instance:GetFullName()`.
It shows how the function behaves when called on an object not in the
`DataModel` hierarchy, and it also shows how the return value does not escape
special characters.


This code sample re-implements the `Class.Instance:GetFullName()` function in
Lua.


Returns a string describing the instance's ancestry. The string is a
concatenation of the `Class.Instance.Name|Name` of the object and its
ancestors, separated by periods. The `Class.DataModel` (`game`) is not
considered. For example, a `Class.Part` in the `Class.Workspace` may
return `Class.Workspace.Part`.

When called on an `Class.Instance` that is not a descendant of the
`Class.DataModel`, this method considers all ancestors up to and including
the topmost one without a `Class.Instance.Parent|Parent`.

This method is useful for logging and debugging. You shouldn't attempt to
parse the returned string for any useful operation; this method does not
escape periods (or any other symbol) in object names. In other words,
although its output often appears to be a valid Luau identifier, it is not
guaranteed.


Instance:GetFullName

Returns a string describing the instance's ancestry.


This method returns the styled or explicitly modified value of the
specified property, or else the default property value if it hasn't been
styled/modified. This differs slightly from accessing the property value
directly, such as `[GuiObject].Rotation`, which returns the default or
modified value of the property.

```lua
local Players = game:GetService("Players")
local ReplicatedStorage = game:GetService("ReplicatedStorage")

local player = Players.LocalPlayer
local playerGui = player.PlayerGui
local HUDContainer = playerGui:WaitForChild("HUDContainer")

local coreSheet = ReplicatedStorage:FindFirstChild("CoreSheet")
local rule = coreSheet:FindFirstChildWhichIsA("StyleRule")
rule.Selector = "TextButton"

-- Reference to a button
local button = HUDContainer:FindFirstChildWhichIsA("TextButton")

print(button:GetStyled("Rotation")) --> 0 (default value)
print(button.Rotation) --> 0 (default value)

-- Apply rotation through style rule property
rule:SetProperty("Rotation", 30)

print(button:GetStyled("Rotation")) --> 30 (styled value based on rule)
print(button.Rotation) --> 0 (default value)

-- Explicitly modify/override styled property
button.Rotation = 45

print(button:GetStyled("Rotation")) --> 45 (modified value)
print(button.Rotation) --> 45 (modified value)
```


Instance:GetStyled

selector

Optional selector for the pseudo instance you are targeting on the
instance.


Returns the styled or explicitly modified value of the specified property,
or else the default property value if it hasn't been styled/modified.


Instance

`Instance` is the base class for all classes in the Roblox class hierarchy
which can be part of the `Class.DataModel` tree.


/reference/engine/classes/ScriptDebuggerService.yaml