# ModuleScripts

Copying code to multiple scripts is time consuming and hard to manage. A better way is to organize and reuse code is by using a <a class="api-link">ModuleScript</a>, a unique type of script that returns a single value, usually a table or function that is useful to multiple scripts.

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<pre class="prettyprint linenums lang-lua">
-- Use require() to get the value returned by a ModuleScript
local Car = require(script.Car)
-- Use a ModuleScript variable
print(Car.topSpeed) --> 120
-- Call a ModuleScript function
Car.honk() --> Beep!
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<figcaption class="figure-caption text-center"><b>CarScript</b> (<code>Script</code> in <span class="text-nowrap"><code>ServerScriptService</code>)</span></figcaption>
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local Car = {}

Car.topSpeed = 120

function Car.honk()
print("Beep!")
end

-- This is returned by require()
return Car
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<figcaption class="figure-caption text-center"><b>Car</b> (<code>ModuleScript</code> within <b>CarScript</b>)</figcaption>
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## Writing ModuleScripts

<a class="api-link">ModuleScripts</a> are commonly placed in ServerScriptService when used by <span class="text-nowrap">server-side</span> Scripts and ReplicatedStorage when used by <span class="text-nowrap">client-side</span> <a class="api-link">LocalScripts</a>. However, <a class="api-link">ModuleScripts</a> can be used when parented to any object, as long as another script has access to it.

When created, a <a class="api-link">ModuleScript</a> starts out with this code:

<pre class="code-line-highlights" data-start="1" data-highlight="">
local module = {}

return module
</pre>

The line `local module = {}` creates an empty table to store the module's contents. This table is then returned (`return module`) so that it's provided to other scripts which require this <a class="api-link">ModuleScript</a>.

You should rename this table (and modify the return line) according to the module’s purpose, such as `PickupManager`. It's also a good idea to rename the ModuleScript to match.

<pre class="code-line-highlights" data-start="1" data-highlight="1;3">
local PickupManager = {}

return PickupManager
</pre>

## Adding to ModuleScripts

To add a function or variable to the table returned by the module, use the **dot notation** as illustrated below.

### Variables

<pre class="code-line-highlights" data-start="1" data-highlight="4">
local PickupManager = {}

-- Add a variable to the module table
PickupManager.maxPickupDuration = 10

return PickupManager

</pre>

### Functions

<pre class="code-line-highlights" data-start="1" data-highlight="4;6">
local PickupManager = {}

-- Add a function to the module table
function PickupManager.getPickupBonus(rarity)

end

return PickupManager
</pre>

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Internal Module Functions/Variables
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If certain variables or functions do **not** need to be exposed outside of the module, you can omit them from the returned table. Below, the `DEFAULT_MULTIPLIER` constant and `RARITY_MULTIPLIERS` table are only used by the module's getPickupBonus() function, so they don't need to be added to the PickupManager table.

<pre class="code-line-highlights" data-start="1" data-highlight="3-9;13">
local PickupManager = {}

local DEFAULT_MULTIPLIER = 1.25
local RARITY_MULTIPLIERS = {
Common = 10,
Uncommon = 20,
Rare = 50,
Legendary = 100
}

-- Add a function to the module table
function PickupManager.getPickupBonus(rarity)
local bonus = RARITY_MULTIPLIERS[rarity] * DEFAULT_MULTIPLIER
return bonus
end

return PickupManager
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## Accessing Modules From Other Scripts

A module script doesn't run its code by itself — another script needs to access it using the built-in require() function. This accepts the ModuleScript as its only argument. For example, if a ModuleScript is located within ReplicatedStorage, you can access it from another script as follows:

<pre class="code-line-highlights" data-start="1" data-highlight="4-5">
local ReplicatedStorage = game:GetService("ReplicatedStorage")

-- Require module
local PickupManager = require(ReplicatedStorage:WaitForChild("PickupManager"))
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The first time `require()` is called on a <a class="api-link">ModuleScript</a>, it will run **once** and return a single value (here, the top-level table `PickupManager`). Calling `require()` again will return the **exact same table**; the module itself will never run multiple times.

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## Calling Module Functions

Once the module is loaded, you can call any of its functions with a similar dot notation format.

<pre class="code-line-highlights" data-start="1" data-highlight="3-9;13">
local PickupManager = {}

local defaultMultiplier = 1.25
local rarityMultipliers = {
common = 10,
uncommon = 20,
rare = 50,
legendary = 100
}

-- Add a function to the module table
function PickupManager.getPickupBonus(rarity)
local bonus = rarityMultipliers[rarity] * defaultMultiplier
return bonus
end

return PickupManager
</pre>

<pre class="code-line-highlights" data-start="1" data-highlight="4;7;8">
local ReplicatedStorage = game:GetService("ReplicatedStorage")

-- Require module
local PickupManager = require(ReplicatedStorage:WaitForChild("PickupManager"))

-- Call function within module
local bonus = PickupManager.getPickupBonus("legendary")
print(bonus) --> 125
</pre>