Rex provides lifecycle hooks and effect utilities for running side effects and managing component mount/unmount logic.

Rex.useEffect(effectFn: (...any) -> ...any, dependencies: {RexState<any>}?): () -> ()

Runs side effects when dependencies change. Supports cleanup functions.

Parameters:

• effectFn: (...any) -> ...any — Effect function to run. Can return cleanup function
• dependencies: {RexState<any>}? — Dependencies to watch. If nil, runs once

Returns: () -> () — Cleanup function

Example:

local count = Rex.useState(0)
Rex.useEffect(function()
    print("Count changed to:", count:get())
    return function()
        print("Cleaning up count effect")
    end
end, {count})

Rex.onMount(callback: () -> (() -> ())?): () -> ()

Runs a function when component mounts. Shorthand for effect without dependencies.

Parameters:

• callback: () -> (() -> ())? — Mount callback, can return cleanup function

Returns: () -> () — Cleanup function

Example:

Rex.onMount(function()
    print("Component mounted!")
    local connection = workspace.ChildAdded:Connect(function(child)
        print("New child added:", child.Name)
    end)
    return function()
        connection:Disconnect()
        print("Mount cleanup")
    end
end)

Rex.onUnmount(callback: () -> ()): () -> ()

Runs a function when component unmounts.

Parameters:

• callback: () -> () — Unmount callback

Returns: () -> () — The callback function (for consistency)

Example:

Rex.onUnmount(function()
    print("Component will unmount")
end)

Rex.useWatch(states: {RexState<any>}, callback: () -> (), options: {immediate: boolean?, deep: boolean?}?): () -> ()

Watches multiple states and runs callback when any of them change.

Parameters:

• states: {RexState<any>} — Array of states to watch
• callback: () -> () — Callback to run when states change
• options: {immediate: boolean?, deep: boolean?}? — Watch options

Returns: () -> () — Disconnect function

Example:

local health = Rex.useState(100)
local mana = Rex.useState(50)
local level = Rex.useState(1)
Rex.useWatch({health, mana, level}, function()
    print("Player stats changed!")
end, {immediate = true})