How to use Modulescripts instead of _G?

##Module Scripts

Module Scripts are scripts that can store anything. This can be given to both the client and server. _G lacks on this ability.

NOTE: When I say array, it is technically the same thing as a table

Let's start by setting up our first ModuleScript code

Let's insert our first module script in ReplicatedStorage

local module = {}

return module

This table is being returned at the end of our module script. I will explain later on why our return is very useful.

Let's put our first function inside of here

local module = {}

function module.announce()
	print("This function is in a module")
end

-- You can store variables as well.
module.Var1 = "hi"
module.Var2 = 5
module.Var3 = false
module.NewTable = {}

return module

NOTE: Values in ModuleScripts must be global(after looking at incapaz's anwser)

Just like arrays, you can insert values.

##How to use ModuleScripts

Now that we have set up our ModuleScript, how can we use this? We have a built-in function called require(). This returns what we have returned in our ModuleScript(remember our module array)

local moduleScript = require(game.ReplicatedStorage.ModuleScript)

moduleScript.announce() -- Now we can call the function announce

You can use moduleScript.announce() in a LocalScript as well(You could not do this if you were to use _G)

##Private Modules

A cool thing about ModuleScripts is that you can take an ID of a ModuleScript and require it.

Let's take an example!

local privateModule = require(0431449) -- This isn't a real ID but I think you get the point
privateModule.PrintFunc()

A huge downside to this is that you can't test it in studio. Especially when you have to test a game that heavily relies on Private Modules. Another downside that can be countered is that an exploiter can require the private module, then, parent it to a Data Model, save the game and then steal your private module. To easily counter this, place script = nil on the top of the ModuleScript.

I am hoping this helped you understand ModuleScripts and why you should use it over _G