Event

Overview

Events are used to implement necessary functions for various situations that occur within the game (such as entering, collisions, etc.).

Linking a Function to an Event

Use :Connect() to link a function to an event.

local Part = script.Parent

local function OnTouched(otherPart)
  print("otherPart : ", otherPart.Name)
end
Part.Touched:Connect(OnTouched)

Unlinking a Function from an Event

If you store the returned value in a variable when you use :Connect() to link a function to an event, you can unlink the function from the event when it is no longer needed.

local Part = script.Parent
local Connection = nil

local function OnTouched(otherPart)
    local partParent = otherPart.Parent
    local humanoid = partParent:FindFirstChild("Humanoid")
 
    if humanoid then
        if Connection ~= nil then
            Connection:Disconnect()	
        end
    end
end
Connection = Part.Touched:Connect(OnTouched)

Commonly Used Events

Collision Events

Detects objects that collide with an object to which the event is linked. (For example: Detecting characters that touch a Kill Part)

local Part = script.Parent
local Connection = nil

local function OnTouched(otherPart)
    local partParent = otherPart.Parent
    local humanoid = partParent:FindFirstChild("Humanoid")
 
    if humanoid then
        if Connection ~= nil then
            Connection:Disconnect()	
        end
    end
end
Connection = Part.Touched:Connect(OnTouched)

Detects objects that exit the area (collision range) of the object to which the event is linked. (For example: Escaping from a trap floor)

local function OnTouchEnded(otherPart)
    print("TouchEnded : ", otherPart.Name)
end
part.TouchEnded:Connect(OnTouchEnded)

Update Events

An event that is called every frame. (For example: Timer calculations, object movement, physics operations)

local RunService = game:GetService("RunService")
local Timer = 0

local function UpdateEvent(deltaTime)
    Timer = Timer + deltaTime
    
    if Timer >= 3 then
        Timer = 0
        print("Reset!)
    end
end
RunService.Heartbeat:Connect(UpdateEvent)

Player Join/Leave Events

An event that detects players who join the game.

local Players = game:GetService("Players")

local function EnterPlayer(player)
    print("EnterPlayer : ", player.Name)
end
Players.PlayerAdded:Connect(EnterPlayer)

An event that detects players who leave the game.

local Players = game:GetService("Players")

local function LeavePlayer(player)
    print("LeavePlayer : ", player.Name)
end
Players.PlayerRemoving:Connect(LeavePlayer) 

Character Spawn/Death Events

These are events that detect when a character is spawned or when a character dies.

local Players = game:GetService("Players")

local function EnterPlayer(player)
    -- Spawn
    local function SpawnCharacter(character)    
        local humanoid = character:WaitForChild("Humanoid")
        
        -- Die
        local function DeathCharacter()
            print(player.Name, "Die!")
        end
        humanoid.Died:Connect(DeathCharacter)
    end
    player.CharacterAdded:Connect(SpawnCharacter)
end
Players.PlayerAdded:Connect(EnterPlayer)

Button Click Events

An event that is triggered when a button is clicked.

local ScreenGui = script.Parent
local Button = ScreenGui.TextButton

local function OnActivated()
    print("Activated")
end
Button.Activated:Connect(OnActivated)