Dropdown.lua

--[[ LOCAL SCRIPT ]]--
local Dropdown = require(game.ReplicatedStorage.Dropdown)
local Gui = game.Players.LocalPlayer.PlayerGui:WaitForChild("ScreenGui")

local TestList = Dropdown.Create({"one","two","three","four","five"}, Gui)
TestList.Button.Position = UDim2.new(0.5,-50,0.5,-25)

TestList.OnSelect(function(value)
	print("Selected: ", value)
end)

--[[ DROPDOWN MODULE ]]--
Dropdown = {}

function Dropdown.Create(list, parent)
	local newDropdown = {}
	newDropdown.Button = Instance.new("TextButton")
	newDropdown.Active = false
	local sizeX, sizeY = 100, 50
	newDropdown.Button.Size = UDim2.new(0,sizeX,0,sizeY)
	newDropdown.Button.Text = list[1]
	newDropdown.Button.Parent = parent
	
	newDropdown.Listeners = {}
	
	function newDropdown:HideList(bool)
		if bool then
			newDropdown.Button.ClipsDescendants = true
		else
			newDropdown.Button.ClipsDescendants = false
		end
		newDropdown.Active = not bool
	end
	
	newDropdown.Listeners.OnSelect = {}
	function newDropdown.OnSelect(func)
		-- fire when item on list is selected.
		table.insert(newDropdown.Listeners.OnSelect, func)
	end
	function fireOnSelect(value)
		for _,func in pairs(newDropdown.Listeners.OnSelect) do
			func(value)
		end
	end
	newDropdown.Button.MouseButton1Down:connect(function()
		--toggle dropdown
		if newDropdown.Active then
			newDropdown:HideList(true)
		else
			newDropdown:HideList(false)
		end
	end)
	
	for i = 1, #list do
		local item = Instance.new("TextButton")
		item.Size = UDim2.new(1,0,0,sizeY)
		item.Position = UDim2.new(0,0,0,sizeY*(i))
		item.Text = list[i]
		item.Parent = newDropdown.Button
		item.MouseButton1Down:connect(function()
			newDropdown.Button.Text = list[i]
			fireOnSelect(list[i])
			newDropdown:HideList(true)
		end)
	end
	newDropdown:HideList(true)
	return newDropdown
end

return Dropdown