RunService¶

Supported Class Services NotCreatable NotReplicated Service

Service responsible for all runtime activity and progression of time.

14 Nova members · 28 modern Roblox members not implemented yet

Description¶

RunService contains methods and events for time management as well as for managing the context in which an experience or script is running. Methods like IsClient(), IsServer(), and IsStudio() can help you determine under what context code is running. These methods are useful for ModuleScripts that may be required by both client and server scripts. Furthermore, IsStudio() can be used to add special behaviors for in‑Studio testing.

RunService also houses events that allow your code to adhere to the engine's frame‑by‑frame loop, such as PreRender, PreAnimation, PreSimulation, PostSimulation, and Heartbeat. Selecting the proper event to use for any case is important, so you should read Task Scheduler to make an informed decision.

Context Test Results¶

Environment	`Class.RunService:IsStudio()\|IsStudio`	`Class.RunService:IsClient()\|IsClient`	`Class.RunService:IsServer()\|IsServer`	`Class.RunService:IsEdit()\|IsEdit`	`Class.RunService:IsRunning()\|IsRunning`	`Class.RunService:IsRunMode()\|IsRunMode`
Live (Client)	`false`	`true`	`false`		`true`	`false`
Live (Server)	`false`	`false`	`true`		`true`	`false`
Edit	`true`	`true`	`true`	`true`	`false`	`false`
Collaborative Edit	`true`	`true`	`false`	`true`	`false`	`false`
Run Mode	`true`	`false`	`true`		`true`	`true`
Play Mode (Client)	`true`	`true`	`false`		`true`	`false`
Play Mode (Server)	`true`	`false`	`true`		`true`	`false`
Team Test (Client)	`true`	`true`	`false`		`true`	`false`
Team Test (Server)	`true`	`false`	`true`		`true`	`false`
Luau Execution	`false`	`false`	`true`		`false`	`false`

Inheritance¶

Object → Instance → RunService

Nova inheritance: Instance → RunService

Methods¶

BindToRenderStep Supported Function Given a string name of a function and a priority, this method binds the function to RunService.PreRender.

RunService:BindToRenderStep(string name, int priority, Function function)

Given a string name of a function and a priority, this method binds the function to RunService.PreRender.

The BindToRenderStep() function binds a custom function to be called at a specific time during the render step. There are three main arguments: name, priority, and what function to call.

As it is linked to the client's rendering process, BindToRenderStep() can only be called on the client.

Name¶

The name parameter is a label for the binding and can be used with RunService.UnbindFromRenderStep() if the binding is no longer needed.

local RunService = game:GetService("RunService")

local function functionToBind() end

-- Bind the function above to the binding named "tempBinding"
RunService:BindToRenderStep("tempBinding", 1, functionToBind)
-- Unbind the function bound to "tempBinding"
RunService:UnbindFromRenderStep("tempBinding")

Priority¶

The priority of the binding is an integer; it determines when during the render step to call the custom function. The lower this number, the sooner the custom function will be called. If two bindings have the same priority, the engine will randomly pick one to run first. The default control scripts run with these specific priorities:

Player Input: 100
Camera Controls: 200 For convenience; the RenderPriority enum can be used to determine the integer value to set a binding. For example, to make a binding right before the default camera update, simply subtract 1 from the camera priority level.

When using RenderPriority, remember to use .Value at the end of the desired enum. RunService.BindToRenderStep() will not work if just the enum is used on its own.

local RunService = game:GetService("RunService")

local function beforeCamera(delta)
    -- Code in here will run before the default camera script
end

RunService:BindToRenderStep("Before camera", Enum.RenderPriority.Camera.Value - 1, beforeCamera)

Custom Function and Delta Time¶

The last argument (function) is the custom function to call. This function will be passed one parameter called deltaTime which shows how much time passed between the beginning of the previous render step and the beginning of the current render step.

All rendering updates will wait until the code in the render step finishes. Make sure that any code called by BindToRenderStep() runs quickly and efficiently; if code takes too long, the experience visuals will be choppy.

Roblox reference signature

RunService:BindToRenderStep(name: string, priority: int, function: Function): null

Roblox documentation

IsClient Supported Function Returns whether the current environment is running on the client.

RunService:IsClient(): bool

Returns whether the current environment is running on the client.

If the code that invoked this method is running in a client context (in a LocalScript, in a ModuleScript required by a LocalScript, or in a Script with RunContext set to RunContext.Client), this method will return true. In all other cases, this method will return false.

If this method returns true, the current environment can access client‑only features like RunService.PreRender or Players.LocalPlayer.

Roblox documentation

IsRunMode Supported Function Returns whether a Run playtest has been initiated in Studio.

RunService:IsRunMode(): bool

This method returns whether a Run playtest has been initiated in Studio. It will continue to return true if the simulation has been paused using the Pause button; however, once it has been stopped using the Stop button, it will revert to returning false. Note that Studio only enters "run" mode when a Run playtest (without the user's player character) is initiated. Also note that this method will return false if the simulation was started using RunService.Run().

Roblox documentation

IsRunning Supported Function Returns whether the experience is currently running.

RunService:IsRunning(): bool

Returns whether the experience is currently running. IsRunning() will always return the inverse of IsEdit() except when the simulation has been paused, in which case both methods will return false.

Security: RobloxScriptSecurity

Roblox documentation

IsServer Supported Function Returns whether the current environment is running on the server.

RunService:IsServer(): bool

This method returns whether the current environment is running on the server. If the code that invoked this method is running in a server context (in a Script with RunContext set to RunContext.Server or RunContext.Legacy, or in a ModuleScript required by a Script), this method will return true. In all other cases, this method will return false.

If this function returns true, then the current environment can access server‑only features like ServerStorage or ServerScriptService.

Roblox documentation

IsStudio Supported Function Returns whether the current environment is running in Studio.

RunService:IsStudio(): bool

This method returns whether the current environment is running in Studio. It can be used to wrap code that should only execute when testing in Studio.

Roblox documentation

Pause Supported Function Pauses the experience's simulation if it is running, suspending physics and scripts.

RunService:Pause()

This method pauses the experience's simulation if it is running, suspending physics and scripts. When the simulation is paused, IsRunning() will return false.

Roblox reference signature

RunService:Pause(): null

Security: PluginSecurity

Roblox documentation

Reset Supported Function Deprecated Resets the current game to a waypoint set when RunService.Run() was called.

RunService:Reset()

Resets the current game to a waypoint set when RunService.Run() was called.

The Reset function resets the current game to a waypoint set when Run was called. This method should only be used after Run was called.

Roblox reference signature

RunService:Reset(): null

Nova behaviour: Nova keeps this legacy member for compatibility. Roblox's modern deprecation wording may describe later Roblox behaviour; verify it against Nova before relying on the copied text.

Security: PluginSecurity

Roblox documentation

Run Supported Function Runs the game's simulation, running physics and scripts.

RunService:Run()

Runs the game's simulation, running physics and scripts.

This method runs the experience's simulation (physics and scripts). When the simulation is running, IsRunning() will return true. However, IsRunMode() will only return true if the simulation was started using the Run button in Studio.

Roblox reference signature

RunService:Run(): null

Security: PluginSecurity

Roblox documentation

Stop Supported Function Stops the experience's simulation if it is running.

RunService:Stop()

This method stops the experience's simulation if it is running. When the simulation is stopped, IsRunning() will return false and IsEdit() will return true.

In contrast to the Stop button in Studio, calling this method will not restore the experience to the state it was in prior to the simulation being run. This means any changes made to the experience by the physics simulation and scripts will persist after the simulation has ended.

Roblox reference signature

RunService:Stop(): null

Security: PluginSecurity

Roblox documentation

UnbindFromRenderStep Supported Function Unbinds a function that was bound to the render loop using RunService.BindToRenderStep().

RunService:UnbindFromRenderStep(string name)

Unbinds a function that was bound to the render loop using RunService.BindToRenderStep().

Given a name of a function sent to BindToRenderStep(), this method will unbind the function from being called during PreRender. This is used to unbind bound functions once they are no longer needed, or when they no longer need to fire every step.

If there is no bound function by the given name, this method takes no action and continues without raising an error.

Roblox reference signature

RunService:UnbindFromRenderStep(name: string): null

Roblox documentation

Events¶

Heartbeat Supported Event Fires every frame, after the physics simulation has completed.

Heartbeat(double step)

The Heartbeat event fires every frame, after the physics simulation has completed. The deltaTime argument indicates the time that has elapsed since the previous frame.

This event is when most scripts run. It occurs at the end of each frame and it's also when any waiting scripts are executed, such as those scheduled with the task library. Heartbeat is commonly used for periodic tasks, such as updating core game systems like health regeneration.

Following this step, the engine sends property updates and events to the server or clients which are later received as part of the replication receive step.

Roblox reference signature

Heartbeat(deltaTime: double)

Roblox documentation

RenderStepped Supported Event Fires every frame, prior to the frame being rendered.

RenderStepped(double step)

Fires every frame, prior to the frame being rendered.

Migration Note¶

This event has been superseded by PreRender which should be used for new work.

Roblox reference signature

RenderStepped(deltaTime: double)

Roblox documentation

Stepped Supported Event Fires every frame, prior to the physics simulation.

Stepped(double time, double step)

Fires every frame, prior to the physics simulation.

Migration Note¶

This event has been superseded by PreSimulation which should be used for new work.

Roblox reference signature

Stepped(time: double, deltaTime: double)

Roblox documentation

Inherited members¶

Inherited from Instance: 8 properties, 36 methods, 7 events. They are documented on the base class page.

28 modern Roblox member(s) are not implemented yet — expand to inspect

Members declared by Roblox's RunService class (or by a missing base class) that Nova does not expose. Use this list to scope a migration; the compatibility guide has the recommended workaround.

Properties¶

Member	Signature	Status	Notes	Flags
`ClientGitHash`	`ClientGitHash: string`	Not yet	—	ReadOnly, NotReplicated, RobloxScriptSecurity
`FrameNumber`	`FrameNumber: int64`	Not yet	—	ReadOnly, NotReplicated
`RunState`	`RunState: RunState`	Not yet	The current run state of the game's simulation.	NotReplicated, PluginSecurity

Methods¶

Member	Signature	Status	Notes	Flags
`BindToAnimation`	`RunService:BindToAnimation(function: Function, frequency: StepFrequency = Hz30, priority: int = 2000): RBXScriptConnection`	Not yet	Binds a custom function to be called at a fixed frequency before Animators update when fixed simulation is enabled, or immediately before `BindToSimulation` callbacks ot…	—
`BindToSimulation`	`RunService:BindToSimulation(function: Function, frequency: StepFrequency = Hz30, priority: int = 2000): RBXScriptConnection`	Not yet	Binds a custom function to be called at a fixed frequency which is independent of the frame rate.	—
`GetControlAndVariantRolloutFlags`	`RunService:GetControlAndVariantRolloutFlags(): Tuple`	Not yet	—	RobloxScriptSecurity
`GetCoreScriptVersion`	`RunService:GetCoreScriptVersion(): string`	Not yet	—	RobloxScriptSecurity
`GetPhysicsStepId`	`RunService:GetPhysicsStepId(): int64`	Not yet	—	RobloxScriptSecurity
`GetPredictionStatus`	`RunService:GetPredictionStatus(context: Instance): PredictionStatus`	Not yet	Checks the PredictionStatus of a specific context instance, useful for debugging scripts affecting multiple instances where some might be…	—
`GetRobloxClientChannel`	`RunService:GetRobloxClientChannel(): string`	Not yet	—	RobloxScriptSecurity
`GetRobloxGuiFocused`	`RunService:GetRobloxGuiFocused(): bool`	Not yet	—	RobloxScriptSecurity
`GetRobloxVersion`	`RunService:GetRobloxVersion(): string`	Not yet	—	RobloxScriptSecurity
`getThrottleFramerateEnabled`	`RunService:getThrottleFramerateEnabled(): bool`	Not yet	—	RobloxScriptSecurity
`GetTotalScriptPlusExecutionTime`	`RunService:GetTotalScriptPlusExecutionTime(): double`	Not yet	—	RobloxScriptSecurity
`IsEdit`	`RunService:IsEdit(): bool`	Not yet	Returns whether the current environment is in `Edit` mode.	PluginSecurity
`IsResimulating`	`RunService:IsResimulating(): bool`	Not yet	Returns whether the client is currently in a resimulation step after a misprediction in the server authority model.	—
`IsTeamTest`	`RunService:IsTeamTest(): bool`	Not yet	—	RobloxScriptSecurity
`Set3dRenderingEnabled`	`RunService:Set3dRenderingEnabled(enable: bool): null`	Not yet	—	RobloxScriptSecurity
`SetPredictionMode`	`RunService:SetPredictionMode(context: Instance, mode: PredictionMode): null`	Not yet	Sets the prediction mode for an Instance to an PredictionMode value.	—
`SetRobloxGuiFocused`	`RunService:SetRobloxGuiFocused(focus: bool): null`	Not yet	—	RobloxScriptSecurity
`setThrottleFramerateEnabled`	`RunService:setThrottleFramerateEnabled(enable: bool): null`	Not yet	—	RobloxScriptSecurity

Events¶

Member	Signature	Status	Notes	Flags
`Misprediction`	`Misprediction(time: double, instances: Array, stats: Dictionary)`	Not yet	In the server authority model, fires during prediction when the engine detects that the client has diverged from the server's authoritative state. Intended for plugin-ba…	—
`PostSimulation`	`PostSimulation(deltaTimeSim: double)`	Not yet	Fires every frame, after the physics simulation has completed.	—
`PreAnimation`	`PreAnimation(deltaTimeSim: double)`	Not yet	Fires every frame, prior to the physics simulation but after rendering.	—
`PreRender`	`PreRender(deltaTimeRender: double)`	Not yet	Fires every frame, prior to the frame being rendered.	—
`PreSimulation`	`PreSimulation(deltaTimeSim: double)`	Not yet	Fires every frame, prior to the physics simulation.	—
`RobloxGuiFocusedChanged`	`RobloxGuiFocusedChanged(isRobloxGuiFocused: bool)`	Not yet	—	RobloxScriptSecurity
`Rollback`	`Rollback(time: double)`	Not yet	In the server authority model, this fires after rolling back the predicted state due to a misprediction, but before resimulation begins.	—

Roblox reference: RunService

Generated from Nova's API dump and Roblox creator-docs. Nova-only members come from the engine's reflection metadata.