The Heartbeat event fires every frame, after the physics simulation has completed. The step argument indicates the time that has elapsed since the previous frame.
As Heartbeat fires every frame, it runs on a variable frequency. This means the rate will vary depending on the performance of the machine. If the game is running at 40 FPS, then Heartbeat will fire 40 times per second and the step argument will be roughly 1/40th of a second.
The step argument can be used to account for the variable frequency of this event, for example:
local RunService = game:GetService("RunService") local RATE_PER_SECOND = 2 RunService.Heartbeat:Connect(function(step) local increment = RATE_PER_SECOND * step end)
There is no guarantee that functions connected to this event will fire at the exact same time, or in any specific order. For an alternative where the priority can be specified, see
The time (in seconds) that has elapsed since the previous frame
Printing Heartbeat Frequency
The following example will print the time between each Heartbeat loop 5 times - while the value of count is less than the value of loopCount.
local RunService = game:GetService("RunService") local loopCount = 5 local count = 0 local connection function onHeartbeat(step) if count < loopCount then count = count + 1 print("Time between each loop: " .. step) else connection:Disconnect() end end connection = RunService.Heartbeat:Connect(onHeartbeat)